DllRegisterServer entry point was not found

'Regasm.exe' is not recognized as an internal or external command,
operable program or batch file.

Where do I get this program?

OK. I found the Regasm program as ran ths command:
Regasm Test1.dll

Microsoft (R) .NET Framework Assembly Registration Utility 2.0.50727.3053
Copyright (C) Microsoft Corporation 1998-2004.  All rights reserved.
Types registered successfully

How does this help me use this DLL in Access now?

Thanks.

The dll is now registered, you should be able to reference it in your Access program.

When I go to Access and try to add it as a reference, I don't see it on the list.

You'll probably need to navigate to it add add it that way.

I'll try that.  However, check this out.

I noticed that TestClass1 attributes COM Class and COM Visible needed to be set to true.  After I did that it chaged my source code.  Notice "
<Microsoft.VisualBasic.ComClass()>" added in front of the class declaration.  I now get a warning:

'Microsoft.VisualBasic.ComClassAttribute' is specified for class '<classname>' but it has no public members that can be exposed to COM; therefore no COM interfaces are generated

<Microsoft.VisualBasic.ComClass()> Public Class TestClass1
    Public Sub New()
        Debug.Print("TestClass1 Init!")
    End Sub
 
    Public Shared Function fnSqrt(ByVal dDblIn As Double) As Double
        Return System.Math.Sqrt(dDblIn)
    End Function
End Class
                                              

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Set COM Visable to True for the function as well.

<Microsoft.VisualBasic.ComClass()> Public Class TestClass1
    Public Sub New()
        Debug.Print("TestClass1 Init!")
    End Sub
 
    <System.Runtime.InteropServices.DispId(1)> _
    Public Shared Function fnSqrt(ByVal dDblIn As Double) As Double
        Return System.Math.Sqrt(dDblIn)
    End Function
End Class
                                              

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Navigating to the DLL dosen't help.

I think regasm registers a .NET assembly into GAC. Now that you have added the COM related attributes, you should be able to use the regsvr32.

I tried regsvr32 again and got the same error message as before:

Test1.dll was loaded, but DllRegisterServer entry point was not found.  This file connot be registered.

you don't need regsvr32. Only regasm.

This might help

http://social.msdn.microsoft.com/Forums/en-US/csharpgeneral/thread/d9e60d0d-7232-4033-979e-1f7bebb8fbc6

OK.  Making progress.

Now when I goto MS Access I can find the Test1 library to reference and use in VBA.  The attached code is function I wrote in VBA in a Access module.  It runs with out error.  However, as you can see it does a whole lot of nothing.

The problem is: the fnSqrt function is NOT visible.  How do I declare that function to make it visible?

************* Function call to DLL in VBA ****************
Function TestTest1() As Double
Dim T1 As New TestClass1
 
Set T1 = Nothing
End Function
 
*********** Source code for DLL in VB *****************
*********** Microsoft Visual Basic 2008 Express Edition
Microsoft.VisualBasic.ComClass()> Public Class TestClass1
    Public Sub New()
        Debug.Print("TestClass1 New!")
    End Sub
 
    <System.Runtime.InteropServices.DispId(1)> Public Shared Function fnSqrt(ByVal dDblIn As Double) As Double
        Return System.Math.Sqrt(dDblIn)
    End Function
 
    Protected Overrides Sub Finalize()
        Debug.Print("TestClass1 Finalize!")
        MyBase.Finalize()
    End Sub
End Class
                                              

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Use the <COMVisible(True)> _ attribute on the function.

Already had done that.  <COM Visable =True>  <DispId = True>  <Value = 1>

Making more progress!  Using some examples I've come up with what you see below.  Now the fnSqrt function IS visible in MS Access.

I use this to rigister the DLL:
C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\RegAsm.exe Test1.dll /tlb:Test1.tlb /verbose

After that I see 'Test1' can be added as a reference in MS Access.

Here is my function in MS Access:
Function TestTest1() As Double
Dim T1 As New TestClass1
Debug.Print T1.fnSqrt(9)
Set T1 = Nothing
End Function

From the immediate widow I try to run the function:
? TestTest1()

An error message box pops up now:
Run-time error '-2147024894 (800700002)':
Automation error
The system cannot fine the file specified.

<ComClass(TestClass1.ClassID, TestClass1.InterfaceId, TestClass1.EventsId)> _
Public Class TestClass1
#Region "COM GUIDs"
    Public Const ClassID As String = "6DEE5FE7-06CA-4d1d-99E0-C3CFE6C8B3FE"
    Public Const InterfaceId As String = "94BA3D27-2F38-4973-BB61-2126888227A4"
    Public Const EventsId As String = "C8A41666-0EF4-4729-9D1E-A3E2A1893CDF"
#End Region
 
    Public Sub New()
        MyBase.New()
        MsgBox("New TestClass1", MsgBoxStyle.Information, "TestClass1")
    End Sub
 
    <System.Runtime.InteropServices.DispId(1)> _
    Public Function fnSqrt(ByVal dDblIn As Double) As Double
        Return System.Math.Sqrt(dDblIn)
    End Function
End Class
                                              

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Progress in VB.  I made a new VB console project.  I included a reference to the Test1.tlb  file.  It works!

So, why does it work in VB and not in VBA in MS Access?

Module Module1
    Sub Main()
        Console.WriteLine(("Test DLL"))
        Console.WriteLine((Test1.TestClass1.fnSqrt(9)))
        Console.ReadLine()
    End Sub
 
End Module

                                              

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There could be many problems including the difference in datatypes being used. I dont think Double is a type in MSAccess!

I found this on another web site.

http://www.developmentnow.com/g/21_2008_3_0_0_1050252/Problem-using-Net-2-0-assembly-with-com-client.htm

"Actually, I ended up using the /codebase option with the regasm, and it
started working! I got this help in another forum.

This worked even though I hadn't given the DLL a strongname. There is a
warning when I use regasm that if the DLL doesn't have a strongname it could
interfere with others on the computer; for my particular case this is not a
problem as I will always ever use this one version ONLY (and hopefully will
before too long be replacing the entire VB6 app, so this is a temporary
measure. But there are few temporaries in the world of released software....)

Also, as far as I know you need to unregister and reregister the DLL every
time there's a change, even if the interface doesn't change. Again, this is
not a problem in our case; the batch files to register unregister seem to
work very reliably.

Hope this works for others as well."