Android : Requested extension com.revmob.airextension could not be found

I'm using Flashdevelop and AIR to port my game to Android but I have a problem implementing revmob ads. I followed this tutorial http://dedleysmedley.wordpress.com/2013/08/16/how-to-include-revmob-ane-in-flashdevelop/

but still no luck. It always says "Error: Requested extension com.revmob.airextension could not be found" when I try to build it.

Any help?