Filter Inactive DL's from the LDAP search

hi ,
iam using LDAP to get the DL(distribution lists)names from my domain.but iam getting Inactive DL names also...how to filter inactive DL's from my domain.
is there any filter like that.
please see the below code what iam using....
please help me in this regard.Thanks in advance.


Dim search As DirectorySearcher
Dim entry As DirectoryEntry
Dim count As Integer = 0
Dim txtDlName As String
Dim lstrreutrn As Boolean = False
txtDlName = Request.QueryString("DLnameForLDAP")
Dim lstrDLname As String = txtDlName.Trim()

Dim ldstDL As DataSet = New DataSet()
Dim ldt As DataTable = ldstDL.Tables.Add()
ldt.Columns.Add("DLname", GetType(String))
entry = New DirectoryEntry("LDAP://DC=domain,DC=com") ', Domainwithuser, password);
search = New DirectorySearcher(entry)
search.Filter = "CN=" & lstrDLname & "*"
Dim i As Integer = search.Filter.Length

For Each AdObj As SearchResult In search.FindAll()
If (AdObj.GetDirectoryEntry().SchemaEntry.Name = "group") Then
Dim dr As DataRow = ldt.NewRow()
dr("DLname") = AdObj.GetDirectoryEntry().Name.Substring(3)
If dr("DLname").ToString().Length > 1 Then
ldt.Rows.Add(dr)
End If
count += 1
End If
Next
ldstDL.Tables(0).TableName = "DLDetails"
Return ldstDL.GetXml()