imap-debug, imap-log do not do much with emacs 24

[pramble]

I have problems with nnimap under gnus and want to see what is happening.
I put (setq imap-debug t) (setq imap-log t) ...nnimap-debug and nnimap-log.. in 
my .emacs file.

Under emacs 23 I get the expected log buffers.
Under emacs 24.1 that I just compiled, I do not get the log buffers.

I think I should read the logs before I post a general "help me" question, but 
my problem is surprising. I have 4 mail sources, all of which do imap over port 
993 and use nnimap-stream set to ssl. Three of them work. The fourth gives me 
an authentication failure after compiling and using emacs 24. I am not using 
built in gnutls, but emacs is talking via openssl or gnutls-cli. I am using 
stock gnus.

Anyway, many thanks if anybody could just tell me how to get the log buffers.