Unable to use my HtmlHelper in views

Trying to use my mvc5 project in a new asp.net vNext project, I am unable to use my HtmlHelper that automatically format a textbox.

Here is my helper extension class :

namespace MyNamespace.Helpers
{
    public static class YokoHelper
    {
        public static HtmlString YokoTextBoxFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper,
                                                                    Expression<Func<TModel, TProperty>> expression,
                                                                    string identifiant,
                                                                    string label)
    {
        string htmlString = string.Format("<span class=\"input\">" +
                                                "{0}" +
                                                "<label class=\"input-label label-yoko\" for=\"{1}\">" +
                                                    "<span class=\"label-content label-content-yoko\">{2}</span>" +
                                                "</label>" +
                                            "</span>",
                                            htmlHelper.TextBoxFor(expression, new { @class = "input-field input-yoko", @id = identifiant }),
                                            identifiant,
                                            label);

        return new HtmlString(htmlString);
    }
}

I included a reference to my namespace in my views :

@using MyNamespace.Helpers

And try to use my helper like this :

@Html.YokoTextBoxFor(m => m.Email, "email", "Email")

Any idea of what I am doing wrong ? Or why it doesn't work with vNext ?

Thanks in advance

Edit :

It seems that the first argument has to be an IHtmlHelper instead of HtmlHelper (MVC 6 vs MVC 5).

The modified code is in my answer bellow.