The online.php script, without any modification, only shows who is online now. The ubbthreads.php script does show the maximum number of users. So what exactly are you asking? Did you try to modify your online.php script and it didn't work?
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Please also see our parent organization VNC Web Services if you're in the need of a new UBB.threads Install or Upgrade, Site/Server Migrations, or Security and Coding Services.