Ratings/Reviews not showing up

Hello,

Regarding one of our products launched around 3 months ago, more than 100 units have been sold in last 2-3 months. However not a single rating/review is posted for this product. This appears statistically inconsistent with other products that we are selling. There should have been at least a few ratings by now. I want to ask other sellers is there any chance ratings do not show up because of any listing issues? Any idea how to troubleshoot this issue?