I Need Help, How to add Liveries to a vehicle that doesn't Have Liveries

What I mean is, A vehicle that when you go to the Livery Tab says “There is no Liveries”. I go into the the Flags and make sure there is both FLAG_HAS_LIVERY | FLAG_LIVERY after adding a fake [Name]_Sign_1 to the YTD file, the reset. nothing. the same message “There is no liveries”…

What am i missing? ;-;

did you ever solve this? same problem here