First of all, please make sure, that you use a clean GTA:VC installation - without any other mods - and reinstall it, if needed.
After that, download and install the most up-to-date version of VC-MP (still 0.3z-R2). Please read this post
, to get more detailed help about the current VC-MP.
Please let me know, that after all of these, is it working or not.