Sounds to me like the cable length might be maladjusted. If you were using a double lever to shift, this would manifest itself as difficulty getting onto one of the rings (too much slack to get to the big ring, or too much tension to get to the little ring). But if you're using a triple lever, you can maybe still get to both rings but the FD is not properly aligned with either.

If it's close, you can use the barrel adjuster to adjust cable length. If that doesn't do it, you can try detaching and re-attaching the cable to the FD. But before you reattach, first adjust the lower limit screw to put the FD in the right spot for the small ring. Then put the shift lever in the correct position for the small ring. Pull the cable taut and attach to the FD. Use the barrel adjuster to fine tune.

Note: When I first put my bike together (Ultegra double w/STI), I attached the cable on the wrong side of the fixing bolt. This meant that the FD did not move enough with the cable travel and I had problems with rubbing until I reattached the cable on the other side of the fixing bolt. You want to attach the cable on the side that has a slot.