Backslash Problem?

Hi Guys

I'm back testing OclHashcat and I am having a problem.

I was trying to create a mask to crack a password with a "\" backslash in it and it wouldn't work, it kept exhausting.

So I narrowed it down to "\" as the problem and got its NTLM hash as 31D6CFE0D16AE931B73C59D7E0C089C0 and used mask "?s", but it doesn't crack it.

Am I missing something? Is it a forbidden char or something?

Confused.

Thanks in advance

Rob