Can't reach C# DLL functions


I am trying to use a C# DLL in Unreal by following this method :
In this DLL, I use .NET, so I can’t easily translate the code to C++.

When I reproduced the tutorial with the basic C++ function, it seemed to work fine.
Then, I tested with my DLL.
I have access to the DLL ( [FONT=courier new]FPlatformProcess
[FONT=courier new]::
[FONT=courier new]GetDllHandle
returns something).
[SIZE=14px]The problem is that[/SIZE]
[FONT=courier new]FPlatformProcess
[FONT=courier new]::
[FONT=courier new]GetDllExport
does return Null.
I guess the procName I send is incorrect, but after all my researches I can’t find any way to get the right procName.

Is there a way to get this procName info somewhere ?
Is it possible to do what I am trying to do ?
Is there anything that I am missing ?

If you need more info, feel free to ask.