Qt 4.8 and PostgreSQL 9 deployment and "driver not load"

Question

PostgreSQL

I've been fighting for two days. I built an application in which the PostgreSQL 9 DBMS. On the machine where I write, the application starts and runs. On other machines, it does not want to connect, "driver not load". There are already working applications with MySQL, everything works fine.
Tell me what you need to drag with the application, I have already shoveled the entire Internet, tried all the solutions, but it still does not start.