Ok guys. Fact is there are NO compile errors for BOTH debug and release. Even when I installed the b4a bridge on a Tecno camon C8, it did not report and the log did not show any error. It will snap a pic but fail to upload same while the same app.installed on Huawei Mate 8 Android 6 works. Installing on samsung grand android version 4 works as well.
So if anyone wants to try, can upload the app for test. Thanks