Showjumper,

It's difficult to say what the problem is without knowing what type of
encryption you are using, but if you'd like I have a free component (with
full source code) on my website,
http://www.aboutfortunate.com/default.aspx?page=encrypt that I use for
encrypting and decrypting data. I prefer to use Rijndael encrytion and
that's what the components 128 bit encryption utilizes. Even if you choose
not to use the component itself you should be able to use it's source to fix
up your code.