Vb.net 第二次尝试时Web请求获取响应失败

我写了一个程序，在网站上搜索用户名，下载他们的html主页，找到下一页的链接，然后下载，依此类推。当我第一次运行程序时，用于搜索的get响应正常工作，用于下载所有html页面的get响应正常工作。但是，当我进行第二次搜索时，get响应将失败。我想可能是服务器在一段时间内只允许这么多搜索，但事实并非如此。当我关闭程序并再次运行时，一切又恢复正常。为什么除了最初的尝试之外，get响应在任何尝试中都会失败？您不能将web请求定义为新的，而且一旦web请求得到释放资源的响应，它们似乎无法关闭web请求。是因为我在后台工作人员中运行整个流程吗？我不知道怎么了。就在昨天，我总是可以做我想做的任何搜索

以下是我的搜索表单代码：

Private Sub FormSearch_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    'if the user name is empty then initialize it
    If My.Settings.UserName = "" Then
        My.Settings.UserName = ""
    End If
    'if the current url is empty then initialize it
    If My.Settings.CurrentURL = "" Then
        My.Settings.CurrentURL = ""
    End If
    My.Settings.Save()
End Sub

Private Sub TextBoxUserName_TextChanged(sender As Object, e As EventArgs) Handles TextBoxUserName.TextChanged
    'if the text length of the text box is greater then zero
    If TextBoxUserName.TextLength > 0 Then
        'enable the search button
        ButtonSearch.Enabled = True
    Else
        'disable the search button and set focus on the text box
        ButtonSearch.Enabled = False
        TextBoxUserName.Focus()
    End If
End Sub

Private Sub ButtonSearch_Click(sender As Object, e As EventArgs) Handles ButtonSearch.Click
    'trim the text box of any spaces
    My.Settings.UserName = Trim(TextBoxUserName.Text)
    'if the user name is not equal to null
    If My.Settings.UserName <> "" Then
        'set the current url and test if it exists
        My.Settings.CurrentURL = "*url here*"
        If URLExists(My.Settings.CurrentURL) = True Then
            'save the settings
            My.Settings.Save()
            'return ok for the dialog result and close the form
            Me.DialogResult = Windows.Forms.DialogResult.OK
            Me.Close()
        Else 'cannot find the account
            'set the text box text to null and set focus on it
            TextBoxUserName.Text = ""
            TextBoxUserName.Focus()
        End If
    End If
End Sub

Private Function URLExists(url As String) As Boolean
    'create a new uri
    Dim uriURL As New Uri(url)
    'create a new web request of the uri
    Dim wrRequest As WebRequest = WebRequest.Create(uriURL)
    'set the web request timeout and method
    wrRequest.Timeout = 30000
    wrRequest.Method = "GET"
    'create a new web response
    Dim wrResponse As WebResponse
    Try
        'if the response succeeds then return true
        wrResponse = wrRequest.GetResponse
        Return True
    Catch ex As Exception 'the response failed so return false
        LabelMessage.Text = ex.Message
        Return False
    End Try
End Function

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您需要显示您的代码，以便我们看到发生了什么问题是我没有关闭http web响应。现在它工作得很好。