Mono install error on OS X Yosemite

mono --debug /Volumes/Data/NzbDrone/NzbDrone.exe
Cannot open assembly ‘/Volumes/Data/NzbDrone/NzbDrone.exe’: File does not contain a valid CIL image.

any help?
Thanks in advance.

Fixed it. Someone on the IRC suggested downloading it again. I had tried that before but this time, I let safari download it instead of FOLX.
Thanks again IRC.