memcached and commands via telnet

Hello,
i ve installed Membase Server 1.7.1 and configured it in order to use it as a Memcached solution.

Using the Web console,i ve created a server node and a bucket (memcached type) to use it via the standar port (TCP port 11211) and managed to connect and store/retreived cached items with a .net client.

My problem is that when i use telnet at the same machine to access statistics of the server, the following command:
>stats slabs
fails (returns error)

Other commands like:
>stats

return succesfully

Any idea why this is happening? Both commands are documented at the memcached protocol