Encrypting and signing in the same run

[devilio at gmail.com]

Good afternoon all,

A business partner is asking us to encrypt and sign our files with PGP 
before uploading it on their server.
I decided to use GnuPG as it is said to be compatible.

After having generated keys and added their key to our keyring, I used, 
as said in the man page :
gpg -se -r 'Partner Name' file_to_encrypt.

However, it doesn't seem to meet their requirements. Here's the reply of 
our partner :
"The file is first encrypted and then signed.  Not encrypted and signed 
in the same run."

Our partner has to remove our signature before to be able to decrypt the 
file.
I don't see what I'm doing wrong, even after some searches in manual and 
other sites.

Does anyone see what's going wrong ?
Thanks you in advance for your help,

Sébastien