Loading C# project dll with unmanaged c++ dependency

I created on C# dll library which has reference to some unmanaged c++ dlls. If i create consoled application to test dll and run it works properly.

 static void Main(string[] args)
    {
       MYdll mine = new MYdll();

      string status = mine.GetStatus();
}

But if same dll is used in actual solution with multiple projectsm and same function is called, I get null exception for som object of unmaanged dll, I copied all unmanaged dll to debug folder. Is there any dll or loading of dll I need to do to remove null exception?