“”附近的语法不正确

我认为我的代码是正确的，但是为什么'po_no'附近的错误语法请检查我的代码。出现此类错误的代码有什么问题？我需要一JOIN两个查询吗？我只想使用内部联接显示两个表

try
{
    if (cb_po_search.Text == "")
    {
        MessageBox.Show("Please Enter to Search!");
    }
    else
    {
        string strPRSconn = ConfigurationManager.ConnectionStrings["POSdb"].ConnectionString;

        SqlConnection sc = new SqlConnection(strPRSconn);
        sc.Open();

        string strQry = "SELECT dbo.POMain.po_no, dbo.POMain.issuing_month, dbo.POMain.supplier, dbo.POMain.model, dbo.POMain.category, dbo.POMain.req_number, dbo.POMain.shipment, dbo.POMain.production_month, dbo.POMain.req_time_arrival, dbo.POMain.req_department, dbo.POMain.lead_time, dbo.POMain.order_desc, dbo.POMain.date_emailed, dbo.POMain.date_confirmed, dbo.POMain.date_recieved, dbo.POMain.assumed_arrival, dbo.Shipping.invoice, dbo.Shipping.loading_date, dbo.Shipping.etd, dbo.Shipping.eta_manila, dbo.Shipping.eta_tstech, dbo.Shipping.ata_tstech, dbo.Shipping.shipping_status, dbo.Shipping.remarks FROM dbo.POMain INNER JOIN dbo.Shipping ON dbo.POMain.po_no = dbo.Shipping.po_noWHERE po_no= '" + cb_po_search.Text + "'";

        SqlCommand scmd = new SqlCommand(strQry, sc);

        SqlDataAdapter da = new SqlDataAdapter(strQry, sc);
        DataTable dt = new DataTable();

        SqlDataReader dr = scmd.ExecuteReader();

        while (dr.Read())
        {
            //purchase order
            tb_ponumber2.Text = (dr["po_no"].ToString());
            tb_reqnumber2.Text = (dr["req_number"].ToString());
            cb_supplier2.Text = (dr["supplier"].ToString());
            cb_model2.Text = (dr["model"].ToString());
            cb_category2.Text = (dr["category"].ToString());
            cb_shipment2.Text = (dr["shipment"].ToString());
            ta_description2.Text = (dr["order_desc"].ToString());
            tb_leadtime2.Text = (dr["lead_time"].ToString());
            tb_request2.Text = (dr["req_department"].ToString());

            dt_time_arrival2.Value = DateTime.Parse(dr["req_time_arrival"].ToString());
            dt_arrival2.Value = DateTime.Parse(dr["assumed_arrival"].ToString());
            dt_confirmed2.Value = DateTime.Parse(dr["date_confirmed"].ToString());
            dt_email2.Value = DateTime.Parse(dr["date_emailed"].ToString());
            dt_production_month2.Value = DateTime.Parse(dr["production_month"].ToString());
            dt_recieve2.Value = DateTime.Parse(dr["date_recieved"].ToString());
            dt_issuing_month2.Value = DateTime.Parse(dr["issuing_month"].ToString());
        }
        sc.Close();
   }
}
catch (Exception ex)
{
    MessageBox.Show(ex.Message);
}