One problem we see almost daily is the latch bolt not fully extending out on the Von Duprin 88 and Von Duprin 55 rim device.  People are quick to think the springs are bad, but in 95% of the cases it is a loose crossbar that is causing the problem.   The Von Duprin exit devices (panic hardware), use a Wegde Tite Screw, Wedge Ring, and Wedge.  When the Wedge Tite Screw is tightened, it expands the Wedge Ring, thus tightening the cross bar on the lever arms.  If you can physically move the cross bar so it is not parallel to the door, this is the problem of your latch bolt not extending.