gcode hot end fan (SD3 + Sanguinololu)

I am trying to set up the gcode controlled hot end fan on my SD3 and it's standard sanguinololu board..

I followed these instructions: http://solidoodletips.wordpress.com/201 … ruder-fan/

I have all the parts fitted and wired and the fan runs, but it won't be controlled by gcode. It just runs constantly.

Had a look through other threads but couldn't find an answer.

Any suggestions?