Asterisk can't find sound files?

I’m getting errors like this:

file.c:663 ast_openstream_full: File beep does not exist in any format

For a number of files. I looked in /var/lib/asterisk/sounds and I have files there for them. In this case, there’s a beep.wav.

asterisk.conf has “astvarlibdir => /var/lib/asterisk”, so it seems like that’s the right place to look.

-rw-rw-r-- 1 asterisk asterisk 6852 2012-04-03 12:47 beep.wav

I’m not sure where to go from here.

This is an Ubuntu server with FreePBX 2.10 and Asterisk 1.8.10 installed.