Stopper, l. Bearing

Hi,
I have a 2000 Foreman 450ES that I recently had to replace the left rear hub assembly, the PIPE ASSY., L. HOUSING (came with new bearing and seal). When I reassembled everything and tightened it up, the axle nut on the axle seemed to go in too far - the holes for the cotter pin was outside of the axle nut. Then, I saw in the Final Driven Gear schematic that there is a STOPPER, L. BEARING shown on the axle. When I tried putting this on, I couldn't get the axle nut to even reach the threads at all. Not sure if this is needed or installed correctly (I put it on the axle, up against the bearing/seal). I ended up removing this stopper and having to put a washer on the axle to enable the cotter pin holes to line up within the axle nut.