What does this mean? "uninitialized constant Fog::Compute::Vsphere::Datastore"

I use a project that relies on FOG, I get this error:
```
uninitialized constant Fog::Compute::Vsphere::Datastore
```

This only happens when a another fog process is cloning a template.

I dont have much info, but if I knew what the error meant, maybe I could provide more context. 