2nd fan in Ramps D9 not working

[mediaklan]

Hi u all !
I need a second fan to cool my PLA prints, so I connect one to D9 in ramps 1.4 : but even if the wiring and the fan seems correct, I can't get it to work. Nothing happens. I found some info about sending M106 S255 gcode command from pronterface, but still nothing happens.
Do i need to do something else I'm not aware of ? In the firmware maybe ?
Thanks !

[mediaklan]

Sorry, useless post : the wiring was NOT correct, so I double check and everything's working right now.