Ad not enabled at specific time.

I have an ad node setup with the following details:

Active Date - 07/19/2012 23:59 pm
End Date - 08/19/2012 23:59 pm

Cron runs every 15 minutes on the server and is confirmed working.

The ad didn't go live on the first cron run (00:15am) after the active date. The node was set to unpublished as it was also showing up when it was first created.

Am I missing anything or is the functionality broken.