what version of Dreamweaver do you have?
Are you installing both the Paypal buttons extesnion and the eCommerce toolkit extension?
You should not install both. NOTE: The paypal eCommerce extension recipes does not apply to the paypal buttons extension.
If you are using Dreamweaver CS5, you should not install the eCaoomerce toolkit, or the eCommerce recipes, they are not compatible with that version of Dreamweaver