Поиск/отбор записей в ActiveDirectory

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        'определеям залогиневшегося юзера и домен
        lblDomain.Text = System.Net.NetworkInformation.IPGlobalProperties.GetIPGlobalProperties().DomainName
        lblUser.Text = "Logon: " & GetCurrent.Name
End Sub
 Try
 
            Dim computerHostName As String = ToolStripTextBox1.Text
            Dim domainName As String = lblDomain.Text
            Dim dirCtx As New DirectoryContext(DirectoryContextType.Domain, domainName)
            Using usersDomain As Domain = Domain.GetDomain(dirCtx)
                Using adsearcher As New DirectorySearcher(usersDomain.GetDirectoryEntry())
 
                    adsearcher.Filter = "(&(objectClass=computer)(department=*" + computerHostName + "*))"
 
                    adsearcher.SearchScope = SearchScope.Subtree
 
                    Dim searchResults As SearchResultCollection = adsearcher.FindAll()
 
                    For Each searchResult As SearchResult In searchResults
 
                        Try
                            dn7 = searchResult.Properties("cn")(0)
                        Catch ex As Exception
                            dn7 = " "
                        End Try
 
                        Try
                            dn8 = searchResult.Properties("department")(0)
                        Catch ex As Exception
                            dn8 = " "
                        End Try
 
                         Try
                            dn9 = searchResult.Properties("whenCreated")(0)
                        Catch ex As Exception
                            dn9 = " "
                        End Try
 
                        DataGridView1.Rows.Add(dn7, dn8, dn9)
                     
                        dn7 = Nothing
                        dn8 = Nothing
dn9 = Nothing
 
                    Next searchResult
 
                End Using
            End Using
        Catch ex As Exception
 
        End Try

 DataGridView1.Item(0, rowindex).Value

  For i = 0 To DataGridView1.Rows.Count - 1
            Dim result As Department = GetDepartmentData(DataGridView1.Item(0, i).Value)
            DataGridView1.Item(1, i).Value = result.CN
            DataGridView1.Item(2, i).Value = result.WhenCreated
        Next

Function GetDepartmentData(ByVal Department As String) As Department
        Try
            Dim Result As New Department
            Dim domainName As String = lblDomain.Text
            Dim dirCtx As New DirectoryContext(DirectoryContextType.Domain, domainName)
            Using usersDomain As Domain = Domain.GetDomain(dirCtx)
                Using adsearcher As New DirectorySearcher(usersDomain.GetDirectoryEntry())
                    adsearcher.Filter = "(&(objectClass=computer)(department=*" & Department & "*))"
                    adsearcher.SearchScope = SearchScope.Subtree
                    Dim searchResults As SearchResultCollection = adsearcher.FindAll()
                    For Each searchResult As SearchResult In searchResults
                        Try
                            Result.CN = searchResult.Properties("cn")(0)
                        Catch ex As Exception
                            Result.CN = " "
                        End Try
                        Try
                            Result.WhenCreated = searchResult.Properties("whenCreated")(0)
                        Catch ex As Exception
                            Result.WhenCreated = " "
                        End Try
                    Next searchResult
                End Using
            End Using
            Return Result
        Catch ex As Exception
            Return New Department With {.CN = "", .WhenCreated = ""}
        End Try
    End Function

Public Class Department
    Public Property CN As String
    Public Property WhenCreated As String
End Class