mod_php_memory_usage not working

OK, I've recompiled php 5.0.3 on my 3 web servers with --enable-memory-limit, however using the %{mod_php_memory_usage}n for the LogFormat directive in the apache config still doesn't work. All it reports to the log file is 0 for ever php script that gets ran (reported a '-' before i recompiled php with memory_limit support). It's the same on all 3 of my servers. The LogFormat directive I have looks like this: LogFormat "%h %l %u %t \"%r\" %>s %b PHP:%{mod_php_memory_usage}n \"%{Referer}i\" \"%{User-Agent}i\"" memoryusage memory_get_usage() works fine and any process using up too much memory gets killed successfully, so I know support is definitely compiled in. Thanks, Eric