New app version creation has failed

each time when i try to get a new version to my app im countering the error-
“New app version creation has failed”. what could be the problem?
i dont have any other versions live
i dont have any other draft version
i turn off the call for my app
the app is live and was used
nothing change
just want to add another feature (want to add the “call summary” activity in a new column in my board. tought i can do it only trough app & code )