Subversion - Repo URL requirements

Hi I hope that someone can help me out here. I read somewhere that the URL for a repo must either be a subdomain or use www. Is this true? For example: subdomain.domain.com or www.domain.com. I installed svn using a subdomain and got it working but now I want to install it on a regular domain without the "www" since I already have a SSL cert for that domain.
I installed on this domain and created the repo for it and imported files from within the shell. Everything looked ok and I was able to use a client to checkout files.
The problem is that I was unable to commit changes. I keep getting a 403 not allowed error when I try. All the perms have been checked, rechecked and I have wiped it and started over several times with the same result. The only difference between this domain and the one where I was able to get SVN to work is one is a subdomain and the other isn't and doesn't use www.