cross error msg

[traders10@xxxx]

Arrrgghhh, I hate programming...

getting a syntax error msg on cross as used here

if cross(pdi(), mdi()) then
Xup =1
EptLo = Low()
endif;

and yet, if I say 

buy = cross(pdi(), mdi());

there is no error and things seem to run ok

it has me confused....

Oh second stupid question, how do I create a new system tester file 
within AB.

Trader