Application Express :: Onchange Event On A Column - Value Undefined?

I have a onchange event on a column which calls the following code:
function SetVal(pThis) {
//get the curren row index on change
var currIndex = $('select[name="'+pThis.name+'"]').index(pThis);
var currValue = pThis.Value;
  alert(currValue);
  $s('P21_mat_id_hold',currValue);

}currValue is "undefined"

Where am I missing something?