E-commerce in Wordpress problem

Hello
For Wordpress there is a plugin that allows you to have a shop.
http://www.3g.co.nz/2/?p=16
When I install it and try to click the e-commerce tab i get this :
About
Welcome to the e-commerce panel.

Note: on some setups, the shopping cart may empty on every page load, if this happens, you will have to add this line:

session_start();

to the index.php file in the base wordpress directory.

I looked at the php file and thats all that is in it. Anyone who uses this plugin know what I am doing wrong?