The compiled sample code app cannot be connected to the remote control when installed on the mobile phone

I once installed the app compiled from the sample code on Android studio on my mobile phone, which can be connected to the remote control of Dajiang UAV, but I updated the code. The recompiled app can't be connected to the remote control, and the previous version of app can't be connected. I don't know why.The app on the mobile phone is shown below: enter image description here