cutting out the centre of an object

Hi all.

Im having a real problem with this. Im trying to cut out the centre of the letter R below. Normally I break curve apart, select the centre, and trim it from the outer. I can then select the centre piece and remove it. As you can see, this has worked with the letters P & O. When I do it with the R it seems to have worked, to the point where I can even select the centre and remove it, but when I put it back over a coloured background, it is still white. Anybody know the answer?