Php – Xdebug – no profile or trace output

I'm at a bit of a loss trying to get profiling and tracing working with Xdebug (debugging works fine). What's worse is that I have it working just fine on a different server/client setup, but I can't seem to see the difference that and this developer workstation using localhost. Nothing is being output to xdebug.log, either.

Server: Ubuntu 10.04, PHP 5.3.2, Xdebug 2.2.1

php.ini:

xdebug.profiler_enable=0
xdebug.profiler_enable_trigger=1
xdebug.profiler_append = 1 
xdebug.profiler_output_dir="/var/www/xdebug-profiles"
xdebug.profiler_output_name="xdebug-profile.%t.%p"

xdebug.auto_trace=0
xdebug.trace_enable_trigger=1
xdebug.trace_options = 1 
xdebug.collect_params=4
xdebug.collect_return=1
xdebug.trace_format=2
xdebug.trace_output_dir="/var/www/xdebug-traces"
xdebug.trace_output_name="trace.%t.%p"

xdebug.file_link_format="xdebug://%f@%l"
xdebug.remote_log="/var/www/xdebug.log"

The obvious answer is "permissions!" Unfortunately, I'm pretty sure that's not it:

# ls -ld /var/www/xdebug-profiles/
drwxrwxrwx 2 www-data www-data 4096 2013-01-02 10:40 /var/www/xdebug-profiles/

Using Firebug, I can see that the xdebug cookies are definitely set in the browser to trigger profiling and tracing. However, even when I disable triggered and enable global in php.ini, I still don't get any output.

Anyone have any ideas? I'm fresh out…