When I install a hack, and I receive an error message, I figure one of three things has happened:
1. I forgot to upload in ASCII.
2. I didn't CHMOD the files correctly.
3. I installed the hack incorrectly.
Obviously the first two are relatively easy to fix. With the third, I examine each line of code I was supposed to hack and make sure that it was the way it was supposed to be.
If I've gone through those 3 steps and I'm positive everything is set, then the obvious conclusion is that there is a problem with the code in the hack itself. Posting here is one way to get to the bottom of that.
I've gone through this convoluted explanation to just say that I've been able to install this hack to my 6.2.1.1 board, and it's been working like a charm ever since.
So, did you try to install this with the Multihack file I created? If that's the case, maybe a line of code wasn't found (because of a hack applied previously). If you tried to install it by hand, give the Multihack file a shot.
If you've done all the above, the only other thing I can suggest is to post the URL to your site so someone can go and look and see what is going on with your code. (Provided, of course, the hacked files are still online)