No feature found in source

[AxelDmt]

Hello,
I have some data in my database that the code well found :

    1 file(s) with supported extensions found
    Connecting to database...
    Retrieving city objects from database...
    59 city objects of type 'CityMBridges' found in the database.
    No feature found in source

What "No feature found in source" really mean ? And how could i fix it to convert bridge citygml objects in 3dtiles ?