They'll go in eventually.
Try another tray!
Great case with a few minor flaws.
Yeh case has been great besides this and the fact i can't use the top drive bay as the top I/O cables block it. These pins really are a pain though and it would have been much easier to use screws. I'm a pretty handy guy and i have spent a good few hours and have yet to get my first drive in... out of a 6 drive raid setup