Excel UDF in Dll

I have read lots of pages on how to make a dll function available for Excel 2003, as a User defined function. For example:

http://www.codeproject.com/KB/COM/ex...select=2576491

With they I have achieved making some dll functions without parameters available for excel as User Defined Functions,

but they don't work with parameters. Worst, when I changed the name of the class, or the main namespace, they stopped working, even after I restored the original names.

I do not get it. Have no idea what is wrong.

I attach a very basic VB.NET 2008 project. It contains two functions:

Code:

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        Public Function TestWithoutParameters() As String
            Return "It looks like it works!"
        End Function
        Public Function TestExcel(ByRef PerÃ*odo As Integer, _
                                  ByRef Precipitación() As Double) As Double()
            Return Precipitación
        End Function

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They don't work. I think is a problem with COM, but no idea.

¿Can someone give me a hint?

Microsoft gives little help.

I attach the project.
This is the main code:

Code:

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Imports System.Math
Imports System
Imports System.Runtime.InteropServices
Imports Microsoft.Win32

Namespace MyNamespace

    <Guid("d2f1d268-a846-4094-9e7f-c9f0be0ab44d")> _
    <ClassInterface(ClassInterfaceType.AutoDual), _
    ComVisible(True)> _
    Public Class FuncionesSPI
        Public Sub New()
        End Sub

        Public Function TestWithoutParameters() As String
            Return "It looks like it works!"
        End Function
        Public Function TestExcel(ByRef PerÃ*odo As Integer, _
                                  ByRef Precipitación() As Double) As Double()
            Return Precipitación
        End Function

        'Para interoperabilidad con excel:
        <ComRegisterFunctionAttribute()> _
        Public Shared Sub RegisterFunction(ByVal t As Type)
            Microsoft.Win32.Registry.ClassesRoot.CreateSubKey("CLSID\{" + t.GUID.ToString().ToUpper() + "}\Programmable")
        End Sub

        <ComUnregisterFunctionAttribute()> _
        Public Shared Sub UnregisterFunction(ByVal t As Type)
            Microsoft.Win32.Registry.ClassesRoot.DeleteSubKey("CLSID\{" + t.GUID.ToString().ToUpper() + "}\Programmable")
        End Sub
        Private Shared Function GetSubkeyName(ByVal type As Type) As String
            Dim S As New System.Text.StringBuilder()
            S.Append("CLSID\{")
            S.Append(type.GUID.ToString().ToUpper())
            S.Append("}\Programmable")
            Return S.ToString()
        End Function

    End Class
End Namespace

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