I believe I have had this problem before on my PMR (I'm not sure if the noids are similar), so I rung up Dye and they said to check the noid for a red bumb. This bumb should be towards the trigger area and gets in the way. So, snip the top of the bump off and it should fit on there properly.
Like I said, this problem was for my PMR when putting on an UL Frame and they may be different principals, please feel free to correct me if I'm wrong
Liam
** BTW I'm not too great on the technical talk **