programming pneumatics

[Aarnat]

Hi all,
This is 2199's first year working with pnumatics. Yesterday we put our "pnumatics board" on last years robot for testing purposes. Prior to yesterday, we had been testing the the compressor and such directly off the battery (of course with fuses etc. so we didn't fry anything) so we know it works. We wired things up with a spike according to the code:

relay8_fwd = !rc_dig_in18; /* Power pump only if pressure switch is off. */

We have Relay 8 for powering the compressor (and plugged into relay 8 on the board) and Pressure sensor plugged into Digital I/O 18 for turning the spike on and off. We measured the voltage with a multimeter and saw 12 volts go into the spike and not coming out to power the compressor. We even told the spike to always be on, but 12 volts still never came out of the spike. We even moved the wires over to another spike and the same thing happened.

Can you tell us what we are missing? Thanks