How to use method from VB6 dll in .NET?

I have ActiveX VB6 DLL (have no access to its sources), and want to call method 'GetUnitInfo'

I use to import it like:

[DllImport(@"C:\Users\R\Documents\lab.dll")]
public static extern long GetUnitInfo(String strRequest, String strInfo, String strName);

But I get an exception:

Unable to find an entry point named 'GetUnitInfo' in DLL

Also I have tryied to load it:

Assembly myAssembly ;
myAssembly = Assembly.LoadFile("C:\\Users\\R\\Documents\\lab.dll");

but getting an exception

The module was expected to contain an assembly manifest. (Exception from HRESULT: 0x80131018)

I have tryied to clean solution, to turn off manifest in project options, to create new manifest file, but it did not helped me...

Found solution, mb someone else will find usefull, (this worked in my case):

1. Create .Net wrapper of VB6 ActiveX dll

   1.1 Run CMD as Administrator

   1.2 Move to .NET SDK folder - cd C:\Program Files\Microsoft SDKs\Windows\v10.0A\bin\NETFX 4.6.1 Tools\ (in my case).

   1.3 Run - TlbImp.exe C:\path_to_old.dll \out: new.dll

2. Register ActiveX dll

   2.1 Run CMD as Administrator

   2.2 Run - regsvr32.exe C:\path_to_old.dll

3. Add Reference to converted dll ("new.dll") in c# project

I used to add "new.dll" reference before registering "old.dll", and was getting following exception

Retrieving the COM class factory for component with CLSID {F2D4F4E5-EEA1-46FF-A83B-A270C92DAE4B} failed due to the following error: 80040154 Class not registered (Exception from HRESULT: 0x80040154 (REGDB_E_CLASSNOTREG))

Cleaning solution, removing reference and following steps 2,3 - helped

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