Modify Hybrid Barrel

[Reignman]

Hey, so I just purchased the new Modify hybrid barrel. It looks great but haven't really had a chance to try it yet. It came with a hop up rubber that was quite thick and it has lines on the inside of it that match up with the ones on the end of the barrel for a better seal etc.

I put the rubber on the barrel and lined up perfectly. I then put it in my brand new King arms advanced metal hop up system. Everything seemed to fit together fine and when I went to shoot it nothing would come out. I switched rubbers to a smaller modify one that still had lines on the inside and the outcome was the same. I then switched it back to the same old hop up rubber that I had (the thinnest one out of the 3) and it worked flawlessly.

Any ideas on as to why the other rubbers wouldnt let the bb pass?