This is a dead topic, but the solution is to install a client adapter along with Subclipse.
Take a look at this, and install SVN Client Adapter, SVNKit Adapter, and SVNKit Library.
Then check under Window -> Preference -> Team -> SVN and make sure there is an entry for SVN Interface.
And for future reference, if you can connect to the repository through the command line, then it must be a problem with the IDE.