Are you sure that you haven't got the mouthpiece in the wrong way around...........
With the frog stud UPWARDS, the ring of the crosspiece should be on the LEFT side as the bayonet is slid into the scabbard.
To be honest, I could never understand why the mouthpiece wasn't symmetrical and allow the bayonet in either way, just like the SMLE or spikes. It didn't make any difference to the blokes because on operations, you just had the scabbard on your pouches or belt wherever it was most comfortable. Even in camp, on guard, ranges or training was the same
