Open the Recording Sessions window double-click the session in question and verify that the Scheduling Enabled checkbox is enabled on the Schedule tab. Also verify that the time and dates are correct.
Check to see if your machine may have been asleep or powered off at the scheduled time. If so, be sure to enable the "Wake Mac and launch WireTap Studio for scheduled sessions" in the General preferences. You may be prompted to install the WireTap Studio Scheduler which is required.
If everything checks out so far, disable the scheduling and click OK. Select your session and click the Start button at the top of the Recording Sessions window. This will start your session immediately, allowing you to see if the URL and application being used are set up properly.
If you still have a problem with that session, select it in the Sessions window, and then click on the Share button. Then send the resulting file, a description of what you are trying to record, including a link or URL to the website of the streaming broadcast if you are trying to record from one, and a description of the specific problem you are having. You can send it all via our support form.