QML Loader issue and vehicle connection

I installed the Qt5.9.2 in non-default directory, I built the QGroundControl from source code with QtCreator. I modified qgroundcontrol-start.sh to point to the downloaded library.
during updating the firmware of the PixHawk, messages like “Controls/Private/Control.qml:88:5: QML Loader: Cannot anchor to an item that isn’t a parent or sibling.” appear on the console and after the update is done, the vehicle doesn’t connect to the QGroundControl.
do you have any idea what I am doing wrong?