Error in Formula variable using Boolean logic

Hello,

I have to create a new formula variable using 2 other formula variables A and B.  If needs to be 0 if A is < 0 or a calculation otherwise.  I used the following Boolean document to get the syntax.

http://help.sap.com/erp2005_ehp_02/helpdata/en/23/17f13a2f160f28e10000000a114084/content.htm?frameset=/en/23/17f13a2f160f28e10000000a114084/frameset.htm

Here is the calculation.  When I try to use it I get the error: "Element Line Discount Test is not correctly defined (please check query definition)."

Thank you for your help,

Susan