You can check the ATE Error on Automated Transaction Log inquiry screen. If you see the below error,
This means that the unit is now at a route step that's expecting CSN but there is no CSN provided in the log file for transaction. That's the reason ATE is rejecting this file.
1) Go to Unit Status screen to check the route step
2) Find the respective process engineer and test engineer to double confirm whether the route is setup correctly.
Action Item: User