LiveCycle Calculation

I created a numeric calculation in LiveCycle Designerusing formcalc. It is very simple (numberfield1 - numberfield 2). I set the display value on all three boxes to display z,zz9.99. The problem that I have is that the first two boxes display fine and the third box (the calculation) drops the decimal point. If I take the calculation out then it displays whatever you type in the box correctly. How do I get the calculation to retain the decimal point.
 
Exmp. 10.00 - 5.00 returns 5 not 5.00.