Normally, this occurs due to lack of true adherence to one specification for the mounting points on M14-type receivers. The mounts are made to USGI specs usually, Springfield and some others aren't always in spec. It's not unusual for a mount to fit VERY poorly while some drop right on and line up fine, depending on the rifle.
I'd return the mount if possible and go with a Sadlak...they'll custom fit it to your gun.
http://www.sadlak.com/si_custom_sm_fitting.html
Otherwise, you'll probably need a good M14 smith that works on mounts to make them fit. You may be part of the problem in how you installed it, but I doubt it. More often than not, it's due to the above-mentioned issue.