ICommands on Button with Parameter WPF Visual Basic

I have a Button that needs to send a Parameter to a Sub when it is Clicked.

I have managed to get the Command to work WITHOUT a Parameter but can't find how to pass the parameter.

My Relay Class

Imports System.Windows.Input
Public Class RelayCommand
    Implements ICommand

    Private _isEnabled As Boolean
    Private ReadOnly _handler As Action

    Public Sub New(handler As Action)
        _handler = handler
    End Sub

    Public Event CanExecuteChanged As EventHandler Implements ICommand.CanExecuteChanged

    Public Property IsEnabled As Boolean
        Get
            Return _isEnabled
        End Get
        Set(value As Boolean)
            If value <> _isEnabled Then
                _isEnabled = value
                RaiseEvent CanExecuteChanged(Me, EventArgs.Empty)
            End If
        End Set
    End Property

    Public Function CanExecute(parameter As Object) As Boolean Implements ICommand.CanExecute
        Return IsEnabled
    End Function

    Public Sub Execute(parameter As Object) Implements ICommand.Execute
        _handler()
    End Sub

End Class

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Welded Class

Imports System.Data.Common
Imports System.Data.SqlClient
Imports System.ComponentModel.DataAnnotations
Public Class ProductionBandsawWelding

    Public Property WeldingComplete As RelayCommand

    Public Sub New()
        SetupCommands()
    End Sub

    Private Sub SetupCommands()
        WeldingComplete = New RelayCommand(AddressOf WeldedNew)
        WeldingComplete.IsEnabled = True
    End Sub

    Public Sub WeldedNew()
        MsgBox("In Welded New")
    End Sub

End Class

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xaml

<StackPanel Grid.Row="6" Orientation="Horizontal" DataContext="{Binding Mode=OneWay, Source={StaticResource ProductionWeldingObjectDataProvider}}">
    <Button Name="OrderCompleteButton" Content="Order Complete" Command="{Binding WeldingComplete}" CommandParameter="OrderCompleteButton.tag" />
</StackPanel>

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I don't think I'm getting the Object out of the Button Tag correctly in the xaml

Any Help would be Appreciated - (Once again a Simple thing in Winforms is made totally complex..)