drake whistle and a woodduck call sounds completely different. Woodducks either want in or they dont, are you using woodduck decoys? if not Id get some and a woodduck call,, dont expect too call them in like you can mallards. if theyre over the dekes and in range,, let them have it!

If youve got speakers on your computer you can hear the different sounds the calls make.
http://www.haydels.com/pages/duckcalls.html