The RadAsyncUpload control is used on forms with other controls, and sometimes we need to validate the control, that is require that the user uploads a file before the form can be submitted.  We have to use a Customvalidator and check the controls client-side properties to see if it has a file.  But if you set the ControltoValidate property an exception occurs.  
Please support this property so that a radAsyncUpload control can be associated with an ASP.Net validator.