.NET v4.0 COM Interop. Can't get Database via late bind? C3D 2012 SP1

[rutar]

Hello!

After resolving trouble with versions changing 107->49, AecXBase, AecXUIBase are now visible, 

I have another one -  m_oAeccDoc.GetType().GetProperty("Database") is null,

in .NET version 3.5 - all works fine,

it happens after changing to .NET version 4.0 and references  to newer ones.

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m_oAcadApp = (IAcadApplication)System.Runtime.InteropServices.Marshal.GetActiveObject(m_sAcadProdID);
if (m_oAcadApp != null)
{
m_oAeccApp = (IAeccApplication)m_oAcadApp.GetInterfaceObject(m_sAeccAppProgId);
m_oAeccDoc = (IAeccDocument)m_oAeccApp.ActiveDocument;

// get the Database object via a late bind - here m_oAeccDoc.GetType().GetProperty("Database") is null

m_oAeccDb = (Autodesk.AECC.Interop.Land.IAeccDatabase)m_oAeccDoc.GetType().GetProperty("Database").GetValue(m_oAeccDoc, null);
}

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Is any possibility to change "Using Interop" Autodesk API Developers guide from .NET 3.5 2010, to v4.0 2012 and also Samples directory files  or  write somwhere  how to use  COM Interop in C3D2012 SP1?

[tomg · Accepted solution]

Take a look at the Answer Solution C# DotNetComInterop Sample.

Tom

[rutar]

Thanks, tomg.

I'd applyed that registry modification (107->49 version) before, to have AecXBase, AecXUIBase visible.

Now changed in  C# ProjectOptions target .NET framework version to 3.5 - all works, 

and it possible to load that dll via netload  and run

in C3D 2012 (autocad.config - using .NET version 4.0) all works fine.

Is it normal application behaivior?