Transferring zip files over wM Flat file adapter

I am using wM v4.2 IO Intelligent Adapter to transfer files between different hosts.
We are able to transfer the normal files (.dat or .xml) using this file IO adapter. But whenever we tranfer the compressed (.zip or .gz) files they get corrupted once tranferred to the Target host system.
Can some body please share your knowledge on this issue.

Murali Mohan