Forks too tight

ed_j Posts: 335
edited July 2012 in Workshop
Really confused. Purchased some 1 1/8 carbon forks (Planet X) for my Principia frame, they go in about halfway then it goes completely solid and it won't push in any further? Strange thing is that it's definitely a 1 1/8 frame and I was supplied a spacer with my stem for 1 inch forks that slips right down the steerer shell. The fork diameter is only 0.3mm thicker but won't go through at all. Measured it all the way down and its the same diameter...

Any ideas would be most appreciated