QLibrary, problem with using external dll, in release

[Jeddite]

Full error message:
The instruction at "0x488b386f" referenced memory at "0x00000001". The memory could not be "read".

And note that you can not use just any library this way.

But, in debug mode everything work!!!This means that i can use this library in that way.

The correct way to use this library is to link to it and include the header files.

How? Simply, add path to library into project file and include header file? But i dont have lib.a file.... this is not my lib, i'm only have lib.dll and function signature.