I think it is more likely that WordPress is still intercepting that page, and redirecting it.
The order in which the re-write rules are placed in the .htacces file sis very important.
This is very similar to the problem with DH installed stats; the actual url involved is different but the problem, and the solution, is the same.
I think you will will find how to fix it by carefully reviewing the DH Wiki page on making stats accessible with .htaccess and substituting your desired url for the "stats' url used in the article's example.
Good Luck, and if you still can't sort it, post back and I'll try to help further.