how to get all details of sql server instances

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C#

VB

SQL

Windows

network

Hi everyone
I'm trying to get all sql server instances and i used these three methods

Private Sub method1()
   Dim mc As New Microsoft.SqlServer.Management.Smo.Wmi.ManagedComputer
   mc.ConnectionSettings.ProviderArchitecture = ProviderArchitecture.Use64bit
   For Each si As ServerInstance In mc.ServerInstances
      cmbInstances.Items.Add(mc.Name & "\" & si.Name)
   Next
End Sub
Private Sub method2()
   Dim dt As DataTable
   dt = System.Data.Sql.SqlDataSourceEnumerator.Instance.GetDataSources
   For Each a As DataRow In dt.Rows
      cmbInstances.Items.Add(a.Item("servername") & "\" & a.Item("instancename"))
   Next
End Sub
Private Sub method3()
   Dim datatable As New DataTable
   datatable = SmoApplication.EnumAvailableSqlServers(false)
   cmbInstances.DisplayMember = "Name"
   cmbInstances.DataSource = datatable
End Sub

But none of these methods seems to be reliable comparing to a "udl" file i create in my windows 7
the udl file always get me a better results than all the above three methods combined .
Any idea?
Kind regards