This is generally what you are trying to do:

            strJavaScript.Append("if (typeof(Page_ClientValidate) == 'function') { ")
            strJavaScript.Append("if (Page_ClientValidate() == false) { return false; }} ")
            strJavaScript.Append("this.value = 'Please wait...';")
            strJavaScript.Append("this.disabled = true;")
            strJavaScript.Append(Page.GetPostBackEventReferenc e(Me.btnSubmit))
            strJavaScript.Append(";")
            btnSubmit.Attributes.Add("onClick", strJavaScript.ToString)

This javascript is added to a button and it disables the button on the client side and calls the btnSubmit_click() event in my code behind when a user clicks it. You get the general idea and should be able to make it work with your application.

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