Thanks. I did all that.
I used all investigating usual methods.
I also removed the 2 code modules of my program with the corresponding modifications in the main, in view to simplify. But B4A added new bugs while claiming again the removed modules, and so on...
It would be too long to list all the verify that i did. I have inspected all the Dims, the library calls, the .bal files, etc.
The B4A V8.50 compiler gives no information. I see no solution.