exec() Permission denied error (127) from PHP

[btidude]

Hello,

I've installed mplayer+mencoder on linux fedora 6 ok and I can run mencoder ok by ssh.

But my problem is, if I try to run mencoder (or any other command) via PHP eg. 'exec(mplayer -args...);' , I get an Permission denied error (127) from exec()

I've tried the full path to the program(s) exec("/root/bin/mencoder -args...") but no luck

PHP is not running in safe mode.. have edited php.ini etc..

I'm kind of a newbie, you can probably tell...

Any ideas for what might be stopping me running programs on the server via exec() from PHP?
Thanks!