Hii
Make sure you have TCP port 989 and 990 open for FTPs. These are the standard ports. make sure you have the same setting on the Ipswitch application..
one thing.. are u having any access-list on the inside interface of the pix ?? if so, add these lines to it
access-list inside permit tcp x.x.x.x x.x.x.x any eq 989
access-list inside permit tcp x.x.x.x x.x.x.x any eq 990
do this and then try...
Raj