How to succesfully use Qt library with Windows DLL project?

[MulliGun]

I have some third party project (SFall- the dll extending original Fallout 2 game). I'd like to add Qt support to the project so i can extend it by some 2d graphic features. I can successfully convert the SFall to Qt supported project and then also successfully compile it, but when I use the newly created ddraw.dll i get this ******* error dialog:

This program requires Windows 95 with DirectX 3.0a or later or Windows
NT version 4.0 with Service Pack 3 or greater

What can be the cause of that error and what can i do to make it to work?
It's very strange that AFTER the project conversion to Qt/MSBuild project when debugging i CAN'T reach very basic and breakpoint set in the DllMain function which is hit without any problems BEFORE project conversion. What the conversion process could have changed with the project setup that the very basic and crucial dll entry point function isn't even called?
Please help!

My specs: *Win10 DirecxX 12, SFall v4.4.4, MSVC 2019 * with Qt VS Tools installed, Qt 5.15.2

Thx. everyone for help!

P.S.
When using the ddraw.dll compiled without Qt support all is OK!

P.S.2
The whole idea of the *SFall *mod is that the generated ddraw.dll is loaded automatically by the original Fallout 2 exe in place of the original dll with this same name (the modified **dll **do it's own job and then, of course loads the original dll)

[hskoglund]

Just a guess, but perhaps you forgot to include some .exe/.dll file properties in your .dll that the original ddraw.dll has, so when Fallout2 checks that dll for compatibility it complains with that error message (before even loading the .dll).

In file explorer, right click on the original ddraw.dll on select Properties and Details:

Try building your version of ddraw.dll so that it shows the same properties.