[ Checkout ] No "add to cart" Option Available

I am having a problem. First I turned off the standard cart option module that comes with gallery (as directed in instructions as they said it was no longer needed) and then installed the most recent versions of checkout module and the checkout by paypal module (downloaded today from sourceforge). I installed, configured them both and activated them. But no "add to cart" button displays on my photo pages. The only time an "add to cart" will display is when I turn on the default cart module that came with gallery - but off course that doesn't go anywhere. You can add photos to your cart all day but there is no checkout process.

What did I miss here? I followed the instructions step by step. In gallery admin is shows both modules as activated, I received no errors while installing and configuring.

Gallery Version 2.1.1
Operating system Linux
Apache version 1.3.34 (Unix)
PHP version 4.4.1
MySQL version 4.0.24-standard
Browser Firefox (also checked in IE 6)

Thanks in advance for the help!!
Kathleen