Password not working on encrypted image file

I added a password using AES192 encryption. The password was 15 letters followed by ## - when I try to open the archive to restore files, it says incorrect password. I am using a UK keyboard, and when I try typing characters, the # is actually producing the / character. What's going on, and how do I get into my archive?

I am trying to access the archive from another pc.

regards

Adam