Departure time validity

I'm trying to schedule a flight  with departure offset of +10 minutes on one day, and get "Departure Time Validity" flagged. All the other fields are ok, slots are available, no other restrictions. I tried other combinations of departure time and departure offset, same result What is the problem? I'm sure this must have turned up before, but the forum software won't let me search for the keywords.

You need to use a new flight number for that particular day/flight

This has to do with the departure time crossing UTC 12 midnight time, resulting in 2 flights with the same flight number on the same day (under UTC time zone) which is not possible.

You need to use a new flight number for that particular day/flight

This has to do with the departure time crossing UTC 12 midnight time, resulting in 2 flights with the same flight number on the same day (under UTC time zone) which is not possible.

So, it's not a bug, it's a feature?

Please read here too:

http://community.airlinesim.aero/topic/8271-departure-time-validity/?hl=%2Bflight+%2Bnumber#entry69559

Not a feature .. it's like in real life