501 Not Implemented error with Alias

Hi, I'm trying to set up a custom virtualhost with the following structure (site-root)/app -> I have the first mapping working, but I can't get the second mapping to give me anything else besides a "501 Not Implemented" error with the text "Not supported" I have a virtual host include file with the following contents Alias "/my-api" "(site-root)/api" LogLevel debug rewrite:trace6
Even with LogLevel set like it is, there is no indication in any log that I can see about what could be causing the 501. I have found only one other person with this problem, and they were trying to alias outside the user's home directory. Any help would be much appreciated!