To be able to track keywords ranking for a product, you will have to add it first to the list of monitored products.
Step 1: Browse to the 'Keywords Tracker' page
Step 2: Click the '+Add Monitored Product' button
To add one of your products, click the dropdown list, select one of your products from the list and click OK.
To add a competitor's product, type the Product ID of the competitor's product and click OK.