Problems using OpenCV on Windows with .dll files

I have had multiple issues trying to get this to work, I am basically evolving a C++ project to go from face detection using circles to also detecting a depth value only using the webcam feed and machine learning (face lbp cascade + onnx depthsense file).
Before, I had Unity crash on me at every game launch.
Now, I put all the old dll files aside and redid my tutorial to copy the C++ file dll and OpenCV dll's in the Asset/Plugins folder and recopied the .xml and .onnx file at the root.
So now, every time I launch it, I get the following error:

DllNotFoundException: UnityOpenCVSample assembly:<unknown assembly> type:<unknown type> membernull)
OpenCVFaceDetection.Start () (at Assets/Scripts/OpenCVFaceDetection.cs:24)

I don't know what could be wrong since I basically just copied all the required dll files. Any ideas on what I could do?

 

Did you check the Inspector for the DLL? Maybe it doesn't have the platform checked that you want to run it on, or maybe it's a 32-bit only DLL but you're building for x64.

More info would help, folder structure, code, inspector settings.

 

Is there an inspector? I think all DLL's have been compiled for x64, I am basically using the third person template and I added the xml and onnx files to the root of the Unity project and the dll's to the Asset/Plugins folder. This can't be an issue related to code since the error states there's a missing dll so I don't know what to say...

 

Click on the DLL file in the Asset/Plugins folder and you'll see Inspector settings for it, as well as some info which platform it supports and all that. If you don't see that, then it's not a (valid) DLL file.

 

They are all made for Windows and recognized for both x86 and x64.

 

Perhaps OpenCVFaceDetection has a dependency on yet another DLL file that isn't included. To me it feels like the most likely cause.

 

This is it, but I don't know what dependency that is anymore, I copied all the .dll's I had in the OpenCV installation folder. And it works, since my OpenCV C++ project compiles normally.