While that may be one reason you cannot start debugging on a server, there are many others as well.

For instance, on an xp box, I have an administrator user account and a regular limited account. Guess which one can't start debugging on the server?

There are permissions issues with debugging - make sure you are part of the Debugger users and VS Developers groups.

There are also other things that can make it go awry.. Check the Microsoft documentation.