Fast Fourirer Using Xilinx ISE

Hi,
   I have an automatically generated code from some source
"cztgen.exe". I am working on performing FFT (C-Z Tfranform).The code
basically has filter (FIR)coefficient computation.I am using two other
code to perform multiplication and
store coefficient/twiddle factors(not that of filter). My problem is I
am not getting write answers when i simulate the codes.The multiplier
and coefficent(not that of filter) codes are working fine. When put
together, I don't get right answer. I suspect there is some problem
with the filter coefficent code.
How do I check the code? and where can I find the source for the
filter coeff. code.If u need the code, I can email it to u.
Thank you.
Hari