Regular Expression filter does not follow the Perl 5.8 rules for single line

Question

When I try to filter the files with the expression

^[\w\s.]+(?:\s-\s)[^-]*

It should allow: E.G. Example - Matching should work.txt

But it should not allow: I.E. Another example - This is ok - but now it should fail.txt

--------------- Regular expression breakdown -------------------
'  Beginning of line or string
'  Any character in this class: [\w\s.], one or more repetitions
'  Match expression but don't capture it. [\s-\s]
'      \s-\s
'          Whitespace
'          -
'          Whitespace
'  Any character that is NOT in this class: [-], any number of repetitions
----------------------------------------------------------------

Comments

Can you provide a description of what you're trying to find? It looks like you're trying to find all files with a single '-' in their name, is that correct?