decryption failed : secret key not available

[bast@altern.org]

Hi,

I'm new on the list and I have a problem ...
I'm also new to gpg and wonder if i've made all the required steps in order to encrypt/decrypt files between two machines.

Machine A :
RedHat Linux 8.0; gnupg-1.2.0

Machine B :
Windows 2000; gnupg-w32cli-1.2.0

I generated keys on both machines, 2048 bits using DSA & ElGamal, exported public keys (still on both) and imported public keys A on B and B on A.

Then I tried encrypting a file.txt on Machine A like this :
# gpg -r "Machine A" -o file.gpg -a --encrypt file.txt

On Machine B :

# gpg -o file.txt --decrypt file.gpg
gpg: encrypted with 2048-bit ELG-E key, ID 012345ABC, created 2002-10-10
      "Machine B (B) <b@b.b>"
gpg: decryption failed: secret key not available

??

I din't find any valuable information on lists and searches, so I wonder if I did all the required steps 
(traditionally, when I don't find a lot of information on my problems, it's a misunderstanding from me ...)

Could someone helps me ?

Thanks,

Bast.