Refreshing values in an Acrobat Form

I have a final grade calculation sheet that works pretty well except for when it refreshes with a new entry or change.  It seems to be lacking behind by one calculation...and I have ensured all the tabs are indeed in the order they need to be.  There's nothing complex about the sheet so I'm at a loss for what I'm missing to make the entire form update with any change in value(s).  The form is below.  Any direction pointing would be greatly appreciated.  Note: I'm a beginner at javascript...the scripts in the form now came from a number of other forums and examples!