I have definitely used this exact set up in the past, for the sake of thoroughness I'll try to be detailed.
Alesis DM6 connected via USB to my desktop into FL Studio 10 (Pro Ed.)
My drivers for the Alesis DM6 are up to date. In fact, FL recognizes the device.. however I'm not getting a midi indicator light when tapping the pads as I should be. My "Audio" setting in FL is set to "ASIO 4ALL v2" (I also tried it with my "Primary Sound Card" as well and nada..) and my "Midi" is selected to my Alesis DM6 "edrum" and input is enabled. I have tried everything I could think of to troubleshoot and that includes looking through countless Youtube vids and relevant troubleshooting threads online to try to isolate my particular issue and have found nothing. I can IM with someone need be, I really need this figured out soon!
Thanks so much for any help anyone can give in advance!