Originally Posted by dsaul

They are usually fairly tight. Lube the o-ring and slide it on the steerer, then wipe the lube off the steerer. It also helps to make sure there is no sharp edge on the cut end of the steerer.

Originally Posted by ljsense

It's just a tighter fit. There's no problem putting some grease on it. You can just wipe off your steer tube with some rubbing alcohol and then put carbon paste on it before you install your stem.

A lot of those headset compression fittings are pretty tight. If your steer tube had a messy cut, you could sand its outer top edge with a little fine sandpaper. That'll help get you going.