Servo not working

I know this is more of a Firefly issue but since none of the solutions there did not work for me, I would like to ask for help here.

So I'm trying to make a servo move in Firefly using a slider(0-180). I can see the Arduino can read and write using the little message panels. When connecting the right pin and setting it to the servo mode, the servo does not move. 

I know the servo works when I try to make it move in Arduino. I also powered the servo using an external power supply but that did not help either. I now have absolutely no idea what I do wrong...

Anyone knows what's wrong?