3 speed front shifter only hitting two marks?
I'm sure that this isn't the right way to say this, but here is what is happening.
Basic old school mountain bike, nothing fancy.
I ran the gear cable through the front derailleur shifter, down the frame, and bolted it in the front derailleaur. When I tried to shift the front shifter it only will click over one position, not two, so only will hit two of the front chain rings, not the three that are there. The same thing happens when I release the shifter.
It sounds as though your high end limit screw needs to be adjusted out, or the derailler is only a two speed derailler.