Http-module LocalPath problem

hi,

I am developing an ejabberd http-module. I am at a point where I need to decode LocalPath variable with base64:decode_to_string. When I use it, I always get the "function clause" error. Can someone tell me how to solve this issue.

process(LocalPath, _Request) ->
decodedInfo = base64:decode_to_string(LocalPath).

Thanks,