vb 浏览器 后退按钮 如何做?

vb 浏览器 后退按钮 怎么做??
是这样的,我想做个简单的浏览器,加那个后退按钮,
可是WebBrowser1.GoBack这样的话,要是刚打开页面返回就会出错,我想要是刚才开的,就让它变成灰色,请哪位高手告我下,怎么做

[解决办法]
‘...我想做个简单的浏览器... '

如果后退按钮都不会做，你还是别浪费时间。
告诉你，将浏览的网页地址放到一数组中。退出时存在Registry或ini文件中。

建议找一个例子看看人家是怎样实现的。
中国最佳VB开源code by Lingll:LE v1.4.56
http://nullvb.go3.icpcn.com/
http://blog.csdn.net/lingll/
[解决办法]
Option Explicit

Dim WithEvents Web_V1 As SHDocVwCtl.WebBrowser_V1

Private Sub Form_Load()
Set Web_V1 = WebBrowser1.Object '初始化Web_V1对象
WebBrowser1.Navigate ( "http://community.csdn.net/ ")
Command1.Enabled = False '前进按钮
Command2.Enabled = False '后退按钮
End Sub

'保证连接在一个窗口打开
Private Sub Web_V1_NewWindow(ByVal URL As String, ByVal Flags As Long, ByVal TargetFrameName As String, PostData As Variant, ByVal Headers As String, Processed As Boolean)
On Error Resume Next
Processed = True
WebBrowser1.Navigate URL
End Sub

'判断能否前进后退,设置对应按键的Enabled属性
Private Sub WebBrowser1_CommandStateChange(ByVal Command As Long, ByVal Enable As Boolean)
On Error Resume Next
If (Command = CSC_NAVIGATEBACK) Then
Command2.Enabled = Enable
End If
If (Command = CSC_NAVIGATEFORWARD) Then
Command1.Enabled = Enable
End If

End Sub

Private Sub Command2_Click()
On Error Resume Next
WebBrowser1.GoBack '后退
End Sub

Private Sub Command1_Click()
On Error Resume Next
WebBrowser1.GoForward '前进
End Sub