Possible Reason #1:
Cookies may not be enabled in your browser or your firewall is not allowing the cookies from PayPal.

Possible Reason #2:
Look at the bottom of the browser window when you open it. 
If you see the following icon in the bottom right part of the window...

...chances are that the security settings in your browser have blocked cookies from being accepted by the checkout company, PayPal.

To check if this is the case:

- Double click the icon to open your privacy report and/or security settings.  You should see the following dialog box.

- Right-Click on https://www.pay.com/cgi-bin/webscr.
- Click "Always Accept cookies from this site."
- Click Close and refresh your browser window by clicking Reload or pressing F5.
- Try adding the item to your cart again.
- If the problem persists, feel free to contact us.