Graph-X不显示图形

Question

我正在使用以下代码在我的VB.Net Forms应用程序中使用Graph-X显示图表 但它只显示缩放控制栏并且没有图表我不知道问题在哪里

      Public Class GraphAreaExample
  Inherits GraphArea(Of DataVertex, DataEdge, BidirectionalGraph(Of DataVertex, DataEdge))
      End Class
'Graph data object
Public Class GraphExample
    Inherits BidirectionalGraph(Of DataVertex, DataEdge)
End Class

'Vertex data object
Public Class DataVertex
    Inherits VertexBase
    <XmlAttribute("text"), DefaultValue("")> _
    Public Property Text() As String

    Public Overrides Function ToString() As String
        Return Text
    End Function
End Class

'Edge data object
Public Class DataEdge
    Inherits EdgeBase(Of DataVertex)
    Public Sub New(ByVal source As DataVertex, ByVal target As DataVertex, Optional ByVal weight As Double = 1)
        MyBase.New(source, target, weight)
    End Sub

    Public Sub New()
        MyBase.New(Nothing, Nothing, 1)
    End Sub

    <XmlAttribute("text"), DefaultValue("")> _
    Public Property Text() As String

    Public Overrides Function ToString() As String
        Return Text
    End Function

End Class
Dim Rand As New Random()

        'Create data graph object
        Dim graph = New GraphExample()

        'Create and add vertices using some DataSource for ID's
        For Each item In DataSource.Take(100)
            graph.AddVertex(New DataVertex() With {.ID = item.ID, .Text = item.Text})
        Next item

        Dim vlist = graph.Vertices.ToList()
        'Generate random edges for the vertices
        For Each item In vlist
            If Rand.Next(0, 50) > 25 Then
                Continue For
            End If
            Dim vertex2 = vlist(Rand.Next(0, graph.VertexCount - 1))
            graph.AddEdge(New DataEdge(item, vertex2, Rand.Next(1, 50)) With {.Text = String.Format("{0} -> {1}",item, vertex2)})
        Next item

Xaml Code

xmlns:graphxctrl="clr-namespace:GraphX.Controls;assembly=GraphX"
xmlns:local="clr-namespace:ShowcaseExample"  

   <graphxctrl:ZoomControl x:Name="gg_zoomctrl">
         <local:GraphAreaExample x:Name="gg_Area"/>
   </graphxctrl:ZoomControl>