gnupg 1.4.7 vs. pgp 6.5.3

[Wolff, Alex]

Company 1 is using gnupg 1.4.7 on SunOS.  Company2 is using PGP 6.5.3 on
Win2003.

Company1 encrypts using Company2's public key and ftp's file in ascii
mode to Company2.

Company2 tries to decrypt file and receives error : 

"bad session keys" or "1 unknown key(s)"

To encrypt we are using command:  gpg -r Charlie.Camut at company.com
--output TEST.txt.pgp --encrypt OUTFILE.go

Is this incompatibility issue between gnupg and pgp or a bonehead
mistake?

Thanks.