null error on class

VbNet · Console

/Program.vb

Imports System
				
Public Module Module1
	Public Sub Main()
		Dim result As New WAWFExport()
        result.StartLine = New WAWFStartLine()
        result.StartLine.NbrTx = 1
		Console.WriteLine(result.StartLine.NbrTx)
	End Sub
	
	 Public Class WAWFExport
		Public Property StartLine() As WAWFStartLine
        Get
            Return m_StartLine
        End Get
        Set(value As WAWFStartLine)
				m_StartLine = value
        End Set
    End Property
    Private m_StartLine As WAWFStartLine
	end class
	
	Public Class WAWFStartLine
    Implements IWAWFFormatter

    Public Property NbrTx() As Integer
        Get
            Return m_NbrTx
        End Get
        Set(value As Integer)
            m_NbrTx = value
        End Set
    End Property
    Private m_NbrTx As Integer
    Private sl As WAWFStartLine



    Public Function format() As String Implements IWAWFFormatter.format
        Return String.Format("START*{0}^", m_NbrTx.ToString)
    End Function
		
	


End Class
	
	Friend Interface IWAWFFormatter
    	Function format() As String
	End Interface
	
	
End Module