FCPX Letterbox Effect trouble.

I'm having some trouble with the Letterbox effect in FCPX. I'm trying to get a widescreen look on my video. I drag the effect unto the clip and change the aspect ratio to 2,35:1. But as you can see from the image I posted nothing changes on the clip and the top and bottom black lines don't appear. Even if I drag the effect and leave it on the default 1,85:1, it should still show lines on both top and bottom as some of you may know. I also exported the clip to see if the letterboxing appeared and it didn't.

Anyone have any suggestions on what I can do? Maybe I'm doing something wrong.
I added a before and after shot for comparison.

You could try my 'Alex4D Widescreen Matte,' a title generator effect. When you add it to your project, all clips below - including titles and transitions - are matted using a variety of aspect ratios including 2.35:1

Download it from alex4d.wordpress.com/2011/07/22/fcpx-widescreen-matte/

It's a long shot, just check one thing..... have you set Spatial conform to 'Fill'

I actually tried changing it to 'Fill' but it didn't fix the problem.

@alex4D Thanks. I'll just use that instead of the letterbox effect. It seems to work really well.

Try setting the clip or clips into a compound clip and applying the effect to the compound.

That is strange. Have you tried checking the effect on other clips, perhaps different codec and timeline settings. or maybe opening a copy of the effect in Motion to see if the copy has the same problem?