beginning-of-defun in cc-mode based languages doesn't work?

[cstacy]

It seems that c-m-a never works for me in cc-mode based languages,
such as csharp-mode.
It always moves to the beginning of the most top-level definition,
such as namespace.
I expected to move to the beginning ot something more local, such as
the current function definition.

(Tried without any init file in most versions of emacs, including 21
and 22.)
I don't think I've ever seen this work (in the last 10 years...)

Are my expectations wrong, or what?