Before adding the add to cart button, make sure the connection to the database is working and test the recordet.
Go to Window -> Bindings to open the Bindings panel, click the plus symbol next to the recordset to show the columns, does this generate a MySQL Error?
If so double check the database connection, go to Window -> Databases to open the database panel. Double click your connection. In the edit connection dialog box, click the test button to test the connection.
If the connection tests OK, please post back with the mySQL Error form the first test and a copy of your page.