Did you try the math routines in the code library on this site? Did you assemble the code you say you got with no errors?

Comments should not show up in the assembled code, only in the list file. The assembled code must be in Intel format. Some assemblers default to Motorola format. Verify that you have properly assembled the code and provide more information.

What simulator?
What assembler?
What switches were set for assembly?
Etc.