According to that documentation:
http://wiki.icomp.de/wiki/DE-9_Joystick#2.2F3_Button_modification
http://wiki.icomp.de/wiki/File:JoystickMod.jpg
to have FIRE2 with C64 the pin 9 has to be pulled to VCC, not to GND.
Right now FIRE2 works with DBAE only if that is pulled to GND -- just like in Amiga, but that will not work for C64.
According to that documentation:
http://wiki.icomp.de/wiki/DE-9_Joystick#2.2F3_Button_modification
http://wiki.icomp.de/wiki/File:JoystickMod.jpg
to have FIRE2 with C64 the pin 9 has to be pulled to VCC, not to GND.
Right now FIRE2 works with DBAE only if that is pulled to GND -- just like in Amiga, but that will not work for C64.