aptitude refuses to install gcc and a few other things

[Hendrik Boom <hendrik@pooq.com>]

I'm running denian-sarge.
When I try to install gcc using aptitude, I get the following lament:

ftp://mirror.direct.ca testing/main gcc-3.31:3.3.4 [ERROR]
 Unable to fetch file, server said '/pub/linux/debian/pool/main//g/gcc-3.3/gcc-3.

I get similar messages for several other files, such as cpp-3.3 gcc-3.3 libgcj-common, mpeglib (I asked for a few other packages, too).

Is there a problem with gcc and friends?
Or with the mirror?
Or (most likely) have I done something wrong?

-- hendrik