You may want to test your VAST zone tag before inserting it into your video player. There are free testers online, including Google's Video Suite Inspector and SpringServe's Ad Tester.

1. Go to the section of the publisher that has the VAST zone ( Your AdButler > Publishers > Your Publisher).
2. In the table of zones, click on the Get Tags button on the far right column of the VAST zone. The Zone Tags window will appear.

3. Make sure that HTTPS (Secure - Recommended) is selected under Protocol. Copy the zone tag.

4. Go to the online tester. Paste the zone tag into the appropriate field then click on the appropriate button to start the test. The screenshot below shows Google's Video Suite Inspector.

5. The tester will attempt to play the ad assigned to the VAST zone, as well as show you an event log. Refer to the log to diagnose any errors in the playback.