Crystal Report

Hello All,
I am facing a problem while trying to invoke crystal report from
Vb. It comes up with an error 20515(which relates to error in
formula), but this does not happen for all the reports it
happens randomly in the sense that for some reports it works out
but not for others and in some case if it comes up then their is
no data displayed. Can anyone help me out, please.
The following is the configuration of my system:
NT 4.0 Workstation
Oracle 7.3.4
VB 5.0
Regional Settings for date dd-MMM-yy
Crystal Report>Options>Date Settings DMY(01-Mar-1999)

Thanks.