How to trigger remote validation for dropdown list

Hi,

I've got drop down list on the form. It's filled in with data from db (Entity Framework). I have also remote validation associated with that dropdown. When I change the value remote validation is launched and everything works.

I added empty value to the dropdown and I'd like to trigger remote validation for that value as well.

@Html.DropDownListFor(m => m.BudgetDirectorateParentID, (SelectList)ViewBag.BudgetDirectorateParentID,"")

How can I do it?