Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

If Not Page.IsPostBack Then
Dim lab As New Label

PlaceHolder1.Controls.Add(lab)
lab.ID = "lab1"
lab.Text = "标签文本"

End If

End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim mylab As Label

mylab = PlaceHolder1.FindControl("lab1")
Dim mystr As String
mystr = mylab.Text
Response.Write(mystr)
End Sub



为什么它就运行错误呢。可以把控件添加到页面。但是为什么在点击按钮取控件值的时候就运行错误了呢,