C# Linking dll static and dynamic

Question

First i will explain my situation. I have a DLL library that is a black box to me. I don't know for sure in what language was it written. My guess it is C++ or even in C, but i don't know. But i DO know that DLL functions so I know how to use it.

Ok. Straight to businesses. I'm writing application C# .NET that will work with that DLL mentioned above. I tried all know to me linking methods but only one works:

• Static: [DllImport("myDll.dll")] - That works.
• Dynamic: by Kernel32.dll LoadLibrary/FreeLibrary - I'm getting exception with code 126 - The specified module could not be found. That problem lays in missing dependence.
• Dynamic: by Reflection - When using Assembly.LoadFile(aPathFileName), I'm getting exception: The module was expected to contain an assembly manifest.

My problem is, that i really need to specify path to my black box dll in some sort of configuration file. Can I ask for any tip what I can do now, how i can resolve this problem? More specific: Is there ANY way to load string from config file and use it to fill constant string, required by static linking DllImport(const string path); or there is another way to dynamic link dll that i don't know?

EDIT

Answer to possible duplicate of another question: Both answers of that question reference to methods i can't use. As i said, i can't use LoadLibrary (exception 126) and also i can't specify loot of possible paths hardcoded (i said that i need load path from config file)

Answer 1

Sinatr posted link to this question, where Cody Gray gave an interesting solution. Static DllImport target path to dll can be override by kernel32.dll SetDllDirectory. All i needed to do was invoke this kernel function

[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
static extern bool SetDllDirectory(string lpPathName);

And then fill it with path saved in my configuration file BEFORE first use of target dll function.

SetDllDirectory(Settings.Default.dllPath);

Important is to set for SetDllDirectory ONLY path to folder where target dll is present (like c:\folder), not full path with name of the dll (like c:\folder\name.dll).