OK, will do.

BUT:
ev = engine_open(NULL) ; in my code is the only place
where i open the engine in my project.

Why in the world would the code that runs perfectly in
A7.10
not run in A7.50 beta if the project code has not been changed ?
unless something has changed in A7.50 beta?

This eludes me.
//
Anyway i have reverted back to A 7.10, just wanted to let you
know in case it is a bug somehow.