用WebBrowser1登录QQ的问题

Private Sub Command1_Click()
    WebBrowser1.Navigate2 "http://ui.ptlogin2.
End Sub

Private Sub WebBrowser1_DocumentComplete(ByVal pDisp As Object, Url As Variant)
    'On Error Resume Next
    If InStr(Url, "ui.ptlogin2.) <> 0 Then '登录页面
        pDisp.Document.getElementById("u").Value = "392354601"      '账号
        pDisp.Document.getElementById("p").Value = "a123456"        '密码
        
        pDisp.Document.getElementById("p").onchange
        pDisp.Document.getElementById("p").Click


        'pDisp.Document.getElementById("verifycode").Value = "xmsz" '验证码
        'pDisp.Document.getElementById("login_button").Click         '登录
    End If
End Sub
'源码如下
Private Sub Command1_Click()
    WebBrowser1.Navigate2 "http://ui.ptlogin2.
End Sub

Private Sub WebBrowser1_DocumentComplete(ByVal pDisp As Object, Url As Variant)
    On Error Resume Next
    If InStr(Url, "ui.ptlogin2.) <> 0 Then '登录页面
        pDisp.Document.getElementById("u").Value = "392354601"      '账号

        pDisp.Document.getElementById("p").Value = "a123456"        '密码
        pDisp.Document.getElementById("p").Click                    '密码框需要手动点击一下,这句没有效果？

        'pDisp.Document.getElementById("verifycode").Value = "xmsz" '验证码

        'pDisp.Document.getElementById("login_button").Click         '登录
    End If
End Sub

直接按登录键不能正确登录 , 会出现验证码的提示框
如果手动点击密码框一下 , 再按登录键则可正常登录
求高手指点