gear box woes

[mart]

ok so it seems like im doing more damage than good.
i did a engine rebuild a few weeks ago and the nc has been sitting without running for some time without testing.
last weekend i had it out for a spin however it wont go above 4th gear.
im positively sure i lined up the shift drum with the neutral lug and the detient star is lined up for neutral. the bike does show neutral however im not entirely sure the fork lifters are sitting on the gears and ln the correct gear drum guides.
when i did the rebuild i moved through the box and in-deed it stopped at 4th, i thought this was down to lack of engine movement.
however i have noticed that the star is just not moving far enough over the next lug to take it into the next gear.
has anyone got any ideas as to were im going wrong