PowerShellGUIのテキストボックスにテキストを動的に入力する

ユーザー作成用のGUIを作成しています。2つのテキストボックスがあります。1つは名用、もう1つは姓用です。GUIでこれらのフィールドの下に名前全体を動的に表示したいと思います。それは可能ですか？ラベルを値とともにそこに配置しようとしましたが、op_Additionが$Display_name_val.Text = $First_name_val.Text + " " + $Second_name_val.Textテキストボックスで認識されていないというエラーが発生しました。ラベルを使おうとしたときも同じです。これには解決策がありますか、それとも表示するために表示名を手動で入力する必要がありますか？ダイアログボックスの完全なコードは次のとおりです。

Add-Type -AssemblyName System.Windows.Forms
[System.Windows.Forms.Application]::EnableVisualStyles()

$AD_user_creation                = New-Object system.Windows.Forms.Form
$AD_user_creation.ClientSize     = '480,600'
$AD_user_creation.text           = "AD user creation - WG Mustang"
$AD_user_creation.TopMost        = $false

$Display_name_lbl                = New-Object system.Windows.Forms.Label
$Display_name_lbl.text           = "User`'s real name"
$Display_name_lbl.AutoSize       = $true
$Display_name_lbl.width          = 25
$Display_name_lbl.height         = 10
$Display_name_lbl.location       = New-Object System.Drawing.Point(10,10)
$Display_name_lbl.Font           = 'Microsoft Sans Serif,10'

$First_name_val                  = New-Object system.Windows.Forms.TextBox
$First_name_val.multiline        = $false
$First_name_val.width            = 120
$First_name_val.height           = 20
$First_name_val.location         = New-Object System.Drawing.Point(200,10)
$First_name_val.Font             = 'Microsoft Sans Serif,10'

$Second_name_val                 = New-Object system.Windows.Forms.TextBox
$Second_name_val.multiline       = $false
$Second_name_val.width           = 120
$Second_name_val.height          = 20
$Second_name_val.location        = New-Object System.Drawing.Point(330,10)
$Second_name_val.Font            = 'Microsoft Sans Serif,10'

$User_name_lbl                   = New-Object system.Windows.Forms.Label
$User_name_lbl.text              = "User logon name"
$User_name_lbl.AutoSize          = $true
$User_name_lbl.width             = 25
$User_name_lbl.height            = 10
$User_name_lbl.location          = New-Object System.Drawing.Point(10,70)
$User_name_lbl.Font              = 'Microsoft Sans Serif,10'

$Display_name_val                = New-Object system.Windows.Forms.Label
$Display_name_val.Text           = $First_name_val.Text + " " + $Second_name_val.Text
$Display_name_val.width          = 250
$Display_name_val.height         = 20
$Display_name_val.location       = New-Object System.Drawing.Point(200,40)
$Display_name_val.Font           = 'Microsoft Sans Serif,10'

$User_name_val                   = New-Object system.Windows.Forms.TextBox
$User_name_val.multiline         = $false
$User_name_val.width             = 250
$User_name_val.height            = 20
$User_name_val.location          = New-Object System.Drawing.Point(200,70)
$User_name_val.Font              = 'Microsoft Sans Serif,10'

$Password_lbl                    = New-Object system.Windows.Forms.Label
$Password_lbl.text               = "Password"
$Password_lbl.AutoSize           = $true
$Password_lbl.width              = 25
$Password_lbl.height             = 10
$Password_lbl.location           = New-Object System.Drawing.Point(10,100)
$Password_lbl.Font               = 'Microsoft Sans Serif,10'

$Password_ini_val                = New-Object system.Windows.Forms.MaskedTextBox
$Password_ini_val.multiline      = $false
$Password_ini_val.width          = 250
$Password_ini_val.height         = 20
$Password_ini_val.UseSystemPasswordChar
$Password_ini_val.location       = New-Object System.Drawing.Point(200,100)
$Password_ini_val.Font           = 'Microsoft Sans Serif,10'

$Password_conf_val               = New-Object system.Windows.Forms.MaskedTextBox
$Password_conf_val.multiline     = $false
$Password_conf_val.width         = 250
$Password_conf_val.height        = 20
$Password_conf_val.UseSystemPasswordChar
$Password_conf_val.location      = New-Object System.Drawing.Point(200,130)
$Password_conf_val.Font          = 'Microsoft Sans Serif,10'

$Location_lbl                    = New-Object system.Windows.Forms.Label
$Location_lbl.text               = "Location"
$Location_lbl.AutoSize           = $true
$Location_lbl.width              = 25
$Location_lbl.height             = 10
$Location_lbl.location           = New-Object System.Drawing.Point(10,160)
$Location_lbl.Font               = 'Microsoft Sans Serif,10'

$Location_val                    = New-Object system.Windows.Forms.TextBox
$Location_val.multiline          = $false
$Location_val.text               = "Domain.com/ADM/Users"
$Location_val.width              = 250
$Location_val.height             = 20
$Location_val.location           = New-Object System.Drawing.Point(200,159)
$Location_val.Font               = 'Microsoft Sans Serif,10'

$Must_chg_pass                   = New-Object system.Windows.Forms.CheckBox
$Must_chg_pass.text              = "User must change password at next logon"
$Must_chg_pass.AutoSize          = $false
$Must_chg_pass.width             = 290
$Must_chg_pass.height            = 20
$Must_chg_pass.location          = New-Object System.Drawing.Point(200,190)
$Must_chg_pass.Font              = 'Microsoft Sans Serif,10'

$Cannot_chg_pass                 = New-Object system.Windows.Forms.CheckBox
$Cannot_chg_pass.text            = "User cannot change password"
$Cannot_chg_pass.AutoSize        = $false
$Cannot_chg_pass.width           = 250
$Cannot_chg_pass.height          = 20
$Cannot_chg_pass.location        = New-Object System.Drawing.Point(200,220)
$Cannot_chg_pass.Font            = 'Microsoft Sans Serif,10'
$Cannot_chg_pass.Checked         = $true

$Pass_not_expires                = New-Object system.Windows.Forms.CheckBox
$Pass_not_expires.text           = "Password never expires"
$Pass_not_expires.AutoSize       = $false
$Pass_not_expires.width          = 250
$Pass_not_expires.height         = 20
$Pass_not_expires.location       = New-Object System.Drawing.Point(200,250)
$Pass_not_expires.Font           = 'Microsoft Sans Serif,10'
$Pass_not_expires.Checked        = $true

$Account_disabled_val            = New-Object system.Windows.Forms.CheckBox
$Account_disabled_val.text       = "Account is disabled"
$Account_disabled_val.AutoSize   = $false
$Account_disabled_val.width      = 250
$Account_disabled_val.height     = 20
$Account_disabled_val.location   = New-Object System.Drawing.Point(200,280)
$Account_disabled_val.Font       = 'Microsoft Sans Serif,10'

$GECOS_lbl                       = New-Object system.Windows.Forms.Label
$GECOS_lbl.text                  = "Description"
$GECOS_lbl.AutoSize              = $true
$GECOS_lbl.width                 = 25
$GECOS_lbl.height                = 10
$GECOS_lbl.location              = New-Object System.Drawing.Point(10,310)
$GECOS_lbl.Font                  = 'Microsoft Sans Serif,10'

$GECOS_val                       = New-Object system.Windows.Forms.TextBox
$GECOS_val.multiline             = $false
$GECOS_val.width                 = 250
$GECOS_val.height                = 20
$GECOS_val.location              = New-Object System.Drawing.Point(200,310)
$GECOS_val.Font                  = 'Microsoft Sans Serif,10'

$ADGroups_lbl                    = New-Object system.Windows.Forms.Label
$ADGroups_lbl.text               = "AD Groups"
$ADGroups_lbl.AutoSize           = $true
$ADGroups_lbl.width              = 25
$ADGroups_lbl.height             = 10
$ADGroups_lbl.location           = New-Object System.Drawing.Point(10,340)
$ADGroups_lbl.Font               = 'Microsoft Sans Serif,10'

$TextBox1                        = New-Object system.Windows.Forms.TextBox
$TextBox1.multiline              = $true
$TextBox1.width                  = 250
$TextBox1.height                 = 160
$TextBox1.location               = New-Object System.Drawing.Point(200,340)
$TextBox1.Font                   = 'Microsoft Sans Serif,10'

$Confirm_Button                  = New-Object system.Windows.Forms.Button
$Confirm_Button.BackColor        = "#00ff00"
$Confirm_Button.text             = "OK"
$Confirm_Button.width            = 100
$Confirm_Button.height           = 30
$Confirm_Button.location         = New-Object System.Drawing.Point(200,550)
$Confirm_Button.Font             = 'Microsoft Sans Serif,10,style=Bold'

$Cancel_button                   = New-Object system.Windows.Forms.Button
$Cancel_button.BackColor         = "#ff0000"
$Cancel_button.text              = "Cancel"
$Cancel_button.width             = 100
$Cancel_button.height            = 30
$Cancel_button.location          = New-Object System.Drawing.Point(350,550)
$Cancel_button.Font              = 'Microsoft Sans Serif,10,style=Bold'

$AD_user_creation.AcceptButton   = $Confirm_Button
$AD_user_creation.CancelButton   = $Cancel_button

$AD_user_creation.controls.AddRange(@($Display_name_lbl,$First_name_val,$Second_name_val,$User_name_lbl,$Display_name_val,$User_name_val,$Password_lbl,$Password_ini_val,$Password_conf_val,$Location_lbl,$Location_val,$Must_chg_pass,$Cannot_chg_pass,$Pass_not_expires,$Account_disabled_val,$GECOS_lbl,$GECOS_val,$ADGroups_lbl,$TextBox1,$Confirm_Button,$Cancel_button))