Some things to consider:
Research the market to see if the pricing is fair on the product you are promoting. Analyze the merchant's sales copy or landing page and try to imagine yourself as a searcher who clicked through - is it very easy to understand & order, or is there a lot of distraction?
Look at your keywords - are they very specific and directly related to the product you are promoting? Or are they general?
Look at your ads - are they a good match for the keywords you are bidding on? Do your ads give specific information about what they can expect when they click through?
You can also email the merchant and ask them to test your affiliate link if you feel it is not tracking.
