unix/pgp to nt/gpg questions

[Nguyen Tuan-ATN014]

I've successfully imported both the public and private keys from unix/pgp to nt/gnupg.  

C:\gnupg>gpg --list-key
c:/gnupg/pubring.gpg
--------------------
pub   768R/5CA8A29D 1996-10-15 bendless<a10226-amt001e>

C:\gnupg>gpg --list-secret-key
c:/gnupg/secring.gpg
--------------------
sec   768R/5CA8A29D 1996-10-15 bendless<a10226-amt001e>

However when I decrypt a pgp file I still get:  

gpg: protection algorithm 1 is not supported
gpg: encrypted with 768-bit RSA key, ID 5CA8A29D, created 1996-10-15
      "bendless<a10226-amt001e>"
gpg: public key decryption failed: unknown cipher algorithm
gpg: decryption failed: secret key not available

Any clues?

Thank you =)