Make red line go away on number entry ?

Hi.

Please see the two images below -- I have a 2 number input components.  The sum of the two must equal 100.  When I put a value in the first, like "20", the line lights up red because 20+0 <> 100.  That's fine.

However, after I put "80" in the second box, the first one still has the red line indicating the original error.

Is there some way to get both lines back to black?

Thanks
Rob