CMOD 7.1 is way Way WAY out of support... It shouldn't be a surprise that it's not working properly. Having said that...
You need to give us more information... You don't say what type of data (AFP? Line Data? PDF? Large Object Support?) or how it's different from other data (age, size, type, etc.).
Make sure you're on the latest version of the client that will work with your server.
(But really, update that software!)
-JD.