Late update to a text field when totalling buttons

Hi I've got 11 radio buttons that get summed by the standard "Value is the sum(+)" in one text field (Subtotal) that I'm trying to use in another text field (Total) to set some text based on the total of the buttons. There seems to be a delay in the values being propagated from Subtotal doing the totalling and the text field(Total) evaluating totals. Like when the button total text field(Subtotal) updates, the other text box that should also "see" the updated value does not until another button is clicked on and then the Total "sees" the previous value and not the updated. Is there a way to synchronize these.
 
Here's the code from the 2nd text field (Total):
var mySubt = getField("Subtotal").value;
var myTotalTxt = getField("Total");
 
if (mySubt <= 0)
{ myTotalTxt.value=" ";
}
else
{ event.value= getField("Subtotal").value;
}
 
When field Subtotal gets updated Total reflects the previous
Subtotal value. Click another Button and Subtotal gets updated
correctly but again Total see preious value that was in Subtotal.
 
What's the trick to fix this?
 
Thanks!!