In this case I am not sure what the scenario you are trying to achieve is. The ShoppingCartItemSelector expects SKUID, which comes from a standalone object called SKU. It contains all the required data for the checkout, like Price, Product image, Tax settings, etc. It is not possible to pass just any object ID there. Any value that you pass to the SKUID will be used to get SKU entry from COM_SKU table.
The alert message means that Kentico tried to look-up a SKU entry based on the ID that you specified. IT found the Apple Ipad 2, which is one of our sample products from the Sample Corporate Site template.
Please refer to Products section of our documentation to learn more about how Product information is stored in Kentico.