Driver alwas not found (windows)

[wirasto]

I tried deploy Qt aplication on other computer (Ms. Windows). But I always get driver not load (mysql).

I copy mysql plugin in plugins and plugins/sqldrivers directory but still not found.
Tried create directory C:/myplugin and load from main.cpp with

QApplication a(argc, argv);
a.addLibraryPath("C:/myplugin");

QApplication a(argc, argv);
a.addLibraryPath("C:/myplugin");

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But, still not found

What's wrong ??

all the time, for deploy on windows I always compile static my qt application.