Not open connection in window vista

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VB

Hi.. friends I have developed a window application in vb.net in which I save & retrieve data from xml file named emp.xml which looks like as

<newdataset>
  <newdataset>
    <pid>0</pid>
    <servername />
    <serverpwd />
  </newdataset>
  <newdataset>
    <pid>1</pid>
    <servername>192.168.2.157</servername>
    <serverpwd>sa1</serverpwd>
  </newdataset>
</newdataset>

I write the following code on the form load and check is it valid connection or not the code of form load is :-

 Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        Dim dt As New DataSet()
        dt.ReadXml(Directory.GetCurrentDirectory().ToString() & "/emp.xml")
        Dim tagValue As String = "1"
        Dim dr As DataRow() = dt.Tables(0).[Select]("PID=" & tagValue)
        If dr.Length <> 0 Then
            ServerName = dr(0)("ServerName").ToString()
            ServerPwd = dr(0)("ServerPwd").ToString()
            Try
                Dim ConCheck As New SqlConnection("Data Source=" & ServerName & "\SQLEXPRESS;Initial Catalog=DUKE_Rathi;User ID=sa;Password=" & ServerPwd)

                ConCheck.Open()'not open connection in window vista, throw exception
                ConCheck.Close()
            Catch ex As Exception
'display this message only in window vista again and again working well in xp and 7
                MsgBox("Incorrect information, Please Enter again")                
            End Try            
        Else
            MsgBox("Please Enter your Server information")
        End If
    End Sub

ServerName and ServerPwd is global variable of string type, My project working well save and retrieve successfully on window xp and window 7 but when I share it on window vista it cannot open the connection throw exception and give message again and again which I give in exception block "Incorrect information, Please Enter again", I shared the exe to all the computers, please help me