做一个VB记事本的感想和遗留下的问题

花了几个星期去完成一个VB实训项目，到今天可以说是告一节了，但是我还是留下一个问题：我的记事本里的打开对话框，当我打开我的对话框，点击“取消”时却出现了如下的错误提示，对此我很不解。我用的是visual studio 2010 VB 写的！我的代码如下：

Sub open_click()
        '单击打开命令的处理过程

        '如果当前编辑的文件内容被更改，提示用户保存文件
        '将选取的文件内容显示到文本框中

        Dim FilStr As String
        Dim TempStr As String
        Dim SaveIt As Integer
        If Modified = True Then
            SaveIt = MsgBox("文件" & Me.Text & "的正文已更改，" & "是否保存更改？", vbYesNoCancel)
            If SaveIt = 2 Then Exit Sub
            If SaveIt = 6 Then
                If FPath_Name <> "" Then
                    SaveFileDialog1.FileName = FPath_Name
                    SaveFileDialog1.Filter = "Text Files(*.txt)|*.txt|" & "All Files (*.*)|(*.*)"
                    SaveFileDialog1.ShowDialog()
                    If SaveFileDialog1.FileName <> "" Then
                        FileOpen(1, SaveFileDialog1.FileName, OpenMode.Output, OpenAccess.Default)
                        Print(1, TextBox1.Text)
                        FileClose(1)

                    End If
                End If
            End If
        End If
        OpenFileDialog1.Filter = "Text Files(*.txt)|*.txt|" & "All Files (*.*)|(*.*)"
        OpenFileDialog1.ShowDialog()
        If Windows.Forms.DialogResult.Cancel = True Then
            Exit Sub
        End If

        If OpenFileDialog1.FileName = "" Then Exit Sub
        FPath_Name = OpenFileDialog1.FileName

        FileOpen(1, OpenFileDialog1.FileName, OpenMode.Input, OpenAccess.Read)

        FilStr = ""
        Do Until EOF(1)
            TempStr = LineInput(1)

            FilStr = FilStr & TempStr
        Loop
        FileClose(1)
        Me.Text = OpenFileDialog1.FileName
        TextBox1.Text = FilStr

    End Sub

当我打开打开对话框，选择“取消”时出现下面的提示：并指到 FileOpen(1, OpenFileDialog1.FileName, OpenMode.Input, OpenAccess.Read)这条语句

请问我该如何修改！