[Spambayes] folder disappeared

[Pei-shan]

I installed your anti-spam program last week.  It worked wonderfully for a
few days.  This morning, as I was admiring the fine job it did over the
weekend (caught 250 spam emails), the 'Spam' folder I setup disappeared
without a trace.  I tried to re-'train' the program and it will not
recognize the folder I newly setup.  i.e. When I tried to 'delete as Spam',
I get a message "You must configure the spam folder". 

Any suggestions?

Pei-shan