Hi Sue,
You don't need any vba for this. Instead, you can code the calculation field
as:
{=BkMrk1-BkMrk2 \# $,0.00;-$,0.00;}
where BkMrk1 and BkMrk2 are the bookmark names of your formfields.
The numeric picture switch (ie '\# $,0.00;-$,0.00;') tells Word how to
display +ve;-ve;0 values. In this case, +ve and -ve values are displayed as
dollars and cents, with a thousands separator. By leaving the third
parameter (ie whatever follows the second semi-colon) empty, you can make
Word display nothing when the result of your calculation is zero.
For more information on Word Field Maths, see my 'tutorial' at:
http://www.wopr.com/cgi-bin/w3t/showthreaded.pl?Number=365442
Cheers