Active Directory - Change Password

Imports System.DirectoryServices

Partial Class _Default
    Inherits System.Web.UI.Page

    Private Sub ChangeUserADPassword(ByVal Username As String, ByVal Password As String, ByVal newPwd As String)
        Dim dcDNS As String = "rockworth.local"
        Dim rootDN As String
        Dim rootDSE As DirectoryEntry
        Dim searchRoot As DirectoryEntry
        Dim userEntry As DirectoryEntry
        Dim searcher As DirectorySearcher
        Dim results As SearchResultCollection
        Dim result As SearchResult
        Dim oldPassword As String = Password
        Dim newPassword As String = newPwd

        Try
            result = Nothing

            rootDSE = New DirectoryEntry(String.Format("LDAP://{0}/rootDSE",dcDNS), Username, oldPassword, AuthenticationTypes.Secure Or AuthenticationTypes.Sealing Or AuthenticationTypes.ServerBind)

            rootDN = DirectCast(rootDSE.Properties("defaultNamingContext").Value, String)
            searchRoot = New DirectoryEntry(String.Format("LDAP://{0}/{1}", dcDNS, rootDN), Username, oldPassword, AuthenticationTypes.Secure Or AuthenticationTypes.Sealing Or AuthenticationTypes.ServerBind)
            '==================================================================
            '------------------------------------------------------------------------
            'Find the user by their username in the directory using the 
            'DirectorySearcher()

            searcher = New DirectorySearcher(searchRoot)
            searcher.Filter = String.Format("sAMAccountName={0}", Username)
            searcher.SearchScope = SearchScope.Subtree
            searcher.CacheResults = False

            results = searcher.FindAll

            '-------------------------------------------------------------------------

            '*****************************************************
            For Each result In results
                userEntry = result.GetDirectoryEntry()
                Exit For
            Next
            userEntry = result.GetDirectoryEntry()
            If userEntry Is Nothing Then
                Label1.Text = "User not found in this domain."
                Exit Sub
            End If

            'Invoke the ChangePassword method (not the SetPassword method, since that 
            'is used by admins to reset a password) 

            userEntry.Invoke("ChangePassword", New Object() {oldPassword, newPassword})
            userEntry.CommitChanges()

            '****************************************************

            Label1.Text = "Password Changed Successfully"

        Catch ex As Exception 'System.Reflection.TargetInvocationException
            Label1.Text = ex.Message

        Finally 'these prevent other memory leaks 
            userEntry = Nothing
            If Not userEntry Is Nothing Then userEntry.Dispose()
            results = Nothing
            If Not results Is Nothing Then results.Dispose()
            searcher = Nothing
            If Not searcher Is Nothing Then searcher.Dispose()
            searchRoot = Nothing
            If Not searchRoot Is Nothing Then searchRoot.Dispose()
            rootDSE = Nothing
            If Not rootDSE Is Nothing Then rootDSE.Dispose()
        End Try

    End Sub

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
        ChangeUserADPassword("5403907", "1234", "1111")
    End Sub
End Class