Not working with Clean URLs

I tried this great module on my localhost and works as expected :)
But when applying on the server I get no results. The blue circle is turning but no suggestions are coming back.
On the network panel of chrome I see that it sends and returns nothing at all. Although if I disable the Clean URLs it works again!
However I need Clean URLs enabled
Could you please suggest a solution or where to look for this kind of problem?
Thanks in advance!