Need help rigging a model

When I try to “Set Parent to: with automatic weights.” It displays an error “bone heat weighting, failed to find solution for one or more bones.”

Also, does my model have to be one mesh to be rigged? When I press L all vertices must be selected but in my case my model consists of multiple meshes.

https://drive.google.com/file/d/0BxDv__ewcb1VbFk5ZlVmcEFqYWs/view?usp=sharing

I cannot get a secure connection to your file, so won’t download it, but the likely cause is a topological error, coincident faces, duplicate vertices, small gaps, etc. You should check the topology of the model first for errors.

Try posting the file to pasteall.org/blend then post the link here.

Cheers, Clock.

It looks like you will need to use envelope weights when you parent it and do some weight painting/setting vertex groups.