The generate date on the Advance Deposit billing item is incorrect.

Manually edit the schedule date for the specified Advance Deposit 
  1. Open the Advance Deposit under Scheduled Activity
  2. Select the Schedule tab and choose to Modify Schedule
  3. Change the dates so that the credits will be generated
Globally change the scheduled dates for Advance Deposits

For more information on troubleshooting Generate Transactions Automatically, follow this solution.