Unmanaged DLL not being found

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C++

C#

Windows

Cordova

The unmanaged DLL is not being found

What I have tried:

I have a cordova project referencing a windows runtime component. This is how I am calling the method from JS

using System;
namespace IBscanUltimate
{
    public sealed class Class1
    {
        public static String getSDK()
        {
            IBscanUltimate.DLL.IBSU_SdkVersion a = new DLL.IBSU_SdkVersion();
            IBscanUltimate.DLL._IBSU_GetSDKVersion(ref a);
            return "SDKVersion: " + a;
        }
}

This is the DLLImport piece which seems to be unable to find the particular DLL:

internal partial class DLL
{
    [DllImport("IBScanUltimate.DLL")]
    private static extern int IBSU_GetSDKVersion(ref IBSU_SdkVersion pVerinfo);
    public static int _IBSU_GetSDKVersion(ref IBSU_SdkVersion pVerinfo)
    {
        int nRc = IBSU_STATUS_OK;
        nRc = IBSU_GetSDKVersion(ref pVerinfo);
        return nRc;
    }
}

Exact error is:

System.DllNotFoundException: Unable to load DLL 'IBScanUltimate.DLL': The specified module could not be found. (Exception from HRESULT: 0x8007007E)

I have placed my DLL in my runtime component as a content file and set the Copy to output to Copy always.

Update 1: I have come across https://msdn.microsoft.com/en-us/library/windows/desktop/hh447159(v=vs.85).aspx This article is explaining that

LoadPackagedLibrary

function can be used to load the dll. I am not seeing any example on how to use this in C#.

Update 2: Specify the search path for DllImport in .NET Mentions that SetDllDirectory or AddDllDirectory can be used. He has a code snippet for SetDllDirectory, but the argument is string[] paths. How would I specify the relative argument?

Update 3:

[DllImport("kernel32.dll", SetLastError = true)]
static extern bool SetDllDirectory(string lpPathName);
public static bool setPath(String path)
{
    //Windows.Storage.
    //return SetDllDirectory("ms-appx:///");
    return SetDllDirectory(path);
}

I tried calling the SetDllDirectory(path) method with various locations that my app should have access to but I am keep getting "false". Few examples that I have tried:

NativeMethods.setPath(Package.Current.InstalledLocation.Path.ToString());
StorageFolder localFolder = Windows.Storage.ApplicationData.Current.LocalFolder;
StorageFolder folder = Windows.Storage.KnownFolders.MusicLibrary;

This is where my app is installed:

C:\Users\AAA\App\hello\platforms\windows\build\windows\Debug\x64\AppX

and I can see that my DLL is there. But still I'm getting the exception that DLL cannot be found. Do I have to put something on the manifest regarding this?