I know you said to put the signature.php in the Forum/ directory, but setting up the cron is not easy for it being in that directory. Just for anyone else to know, you can just put the signature.php file in your includes/cron/ directory and it still works the same without changing any settings. Then you can just use the defaut cron setup.
Here is my working Signature,
I do have a question or two.
How did you add the number online bit. Also the info in my sig is not perfectly calculated to what the board says on members, posts and threads. Is it excluding certain usergroups and forums? members are about 20 off, threads are about 3000 off.