How do a validate using group by

[Tison]

I have a large table as follows
Rec_Type Rec_Month Rec_Year Stuff
A Oct 2004 sdsddsxfdfsdf
A Nov 2004 tyytrtrt
B Oct 2004 rgdrghgdfdf
C Oct 2004 jtyjtjtrjtyjtyjty
C Nov 2004 ererggdfg

I want to select where there is no record for a specific month (eg B has no Nov record)

My problem is that I get all the non Nov records and I only want to get a result that says
"B has no Nov record for 2004