First of all, you're an affiliate promoting products in CB I presume...it's not your own product you're talking about?
Anyways, is your traffic targeted enough to the pitch you're presenting on your landing page? Do they see the answer to what they wanted after reading your ad?
Try playing around a little with the landing page, give them no reason but to buy the product, opt in or what it is you do on your landing page.
I take it you use a landing page?
If nothing seems to improve the convertions, you should choose another product....if it's a big niche, I'm sure there are other products you can promote that may work better for your traffic.
Hope you figure it out!