Bed not turning on, the relay work if i upload blink sketch

I have a ramps 1.4 on mega 2560
After some fw updates the bed stopped working.
To check if it was some electrical problem i uploaded the arduino sketch blink, making the D8 pin blink , and the relay is opening and closing as usual.
So why i cant make the bed turn on with pronterface?
I also tested the voltage on the output and it is totally 0, so i think is software related.
tryed slow pwm with no succes

I have this connections:
D8(BED) D9(EMPTY) D10(HOT END)

Thanks

Edited 2 time(s). Last edit at 08/04/2016 05:29PM by IamTheVector.

Is your heated bed thermiser reading room temperature ?

Yes that was the problem, i was reading a fake room temperature on 27deg so i was fooled. Thanks!