Forms Data Controls :: Validating Dropdown Selection In Footertemplate In Gridview?

I have two dropdowns in the footertemplate of my gridview inside a usercontrol.

I also have a button "btnADD" inside the footer template. I am using the footertemplate to add a new row to the grid.

What do I do to validate on Button_click event for 'btnAdd' if a value is selected in the dropdown other than "select.." which I dynamically add in rowdatabound event?

I have this javascript function that I wanted to implement, but it gets called in the Page_load event rather than the button click event and gives an error.

The javascript function that I need to call is this: ( I created a method to return a string to use it in regards to RegisterClientScriptBlock, but do not know exactly how to use it)

rotected string BuildValidation()
{
StringBuilder sb = new StringBuilder();
sb.Append("<script type='text/javascript'>");
sb.Append("function ValidateWComp() {");

[Code]....