textbox value in an application folder

in vs2005 website,i have a page named page1.aspx. in that page i have a textbox control named Txtrt1. i want this  text box value in a vb file which is in app_code/customtoolbar/cs1.vb.
 
i tried to access the value like as follows
 Dim page As System.Web.UI.Page = System.Web.HttpContext.Current.Handler
            Dim myTextBox As TextBox = page.FindControl("Txtrt1")
            If myTextBox.Text = "" Then Exit Sub
 
but i am getting error like as follows
Unable to cast object of type 'MapInfo.WebControls.MapController' to type 'System.Web.UI.Page'.
 
 
ow can i solve this issue?
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