mjw16

I'm installing some RaceFace Prodigy splined cranks on my new ride and can't seem to get the crank arm to seat completely on the bottom bracket. I know it's critical that the crank arm mate flush with the stopper flange on the bottom bracket, but no matter how hard I tighten the bolt, there is still a 3-5 mm gap on both sides. I greased the splines and checked for burrs or anything else that could cause an improper fit and everything looks fine. I noticed that when I removed and re-installed the crank arm bolt, the crank arms seated a little closer. I've torqued the bolt pretty tight and don't want to over-tighten it in the process. Any ideas on how to get the proper fit?