新人求解~~~~~

新手求教，下面是我在网上找到一段关于异步的代码，我把myPing.SendAsync(ipAddy，ipAddy)改成myPing.Send ( ipAddy )运行就假死，结束调试电脑直接就蓝屏，试了2次都这样，求教这是为什么
Public Class Form1
Private mPingAddresses As New List(Of String)
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
For i As Integer = 1 To 20
mPingAddresses.Add("10.1.1." & i.ToString)
Next
Me.ListBox1.Items.Clear()
For Each ipAddy As String In mPingAddresses
Dim myPing As New Net.NetworkInformation.Ping()
AddHandler myPing.PingCompleted, AddressOf PingRequestCompleted
myPing.SendAsync(ipAddy，ipAddy)
Next
MsgBox("OK")
End Sub
Public Sub PingRequestCompleted(ByVal sender As Object, ByVal e As Net.NetworkInformation.PingCompletedEventArgs)
If e.Reply.Status = 0 Then Me.ListBox1.Items.Add(e.UserState.ToString & " is OK.")
End Sub
End Class