I'm not at my MB2S, so I can't check. However, wouldn't you need to set the track type to velo, press, X volts, or Env to output values on the Mod 1 or Mod 2 jacks?
Perhaps you can set the track to Env and use a 0 attack time envelope as the gate (output through Mod 1 or Mod 2)
If the mod/voltage tracks are anything like the MatrixBrute, the mod values stay at the last set value. So to create a positive edge (trigger) you have to have one step with the mod at 0, then at the max value on the next step (not needed if you can use an envelope).