i have a M-Audio Oxygen 8...i hope this helps you with yours...
hopefully you have installed the drivers, should have came with the keyboard...make sure your controllers in turned on before you start FL...go to "Options" in the file menu and go to "MIDI settings"...on the right side of the box that pops up, under "Remote control input" it should say "In USB Keystation"...if it doesn't select it and everything should work...