Extract unique records into a new database

Good morning,I'm new to the site but also to programming. I train myself on the creation of scriptIdea in order to automate repetitive tasks. Inspired by messages found on your site, I tried to develop the following script to 1) write information in a virtual field to determine unique records based on an ID and a date of action(oldest) see extract unique records directly into a new file. Nothing works. Despite the instruction field.protected= false I get an error message: "Impossible to establish the value of this field. Is the field virtual or protected?".
Thank you in advance for any help you want to give me.
Here is my script:
Function getValue()    Dim db As database    Dim rs As RecordSet    Dim rec As Record    Dim unique As Long        Set db = Client.OpenDatabase(sFilename)    Set table = db.TableDef    CountRecords = db.Count            Set oListeDossiers = CreateObject("Scripting.Dictionary")    For CurrentRecord=1 To CountRecords        Set rs = db.RecordSet            ' Obtain the CurrentRecord from the RecordSet.            rs.GetAt(CurrentRecord)             Set rec = rs.ActiveRecord            sId = rec.GetCharValueAt(1) '  colonne ID            sValue = rec.GetCharValueAt(2) ' colonne Date_Action            currentDate=rec.GetCharValueAt(2)  ' colonne Date_Action                                                                        If Not oListeDossiers.exists(sID) Then                              key = sID                        valeur = sValue                        oListeDossiers.Add key, valeur                         updateField(CurrentRecord )                                            Else                                                     If  currentDate<= oListeDossiers(Sid) Then                                                               updateField(CurrentRecord)                                                        End If                                      End IfNext CurrentRecord            Set rec = Nothing        Set rs = Nothing    Set db = NothingEnd FunctionFunction updateField(ByVal activeRec As String)    Dim db As database    Dim table As table    Dim field As field    Dim rs As Object    Dim rec As Object    Dim i, j As Long    Dim n As Long    Dim vAnneeRole As String    Dim vDateMer As String    Dim vNom As String    Dim vAction As String    Dim vUnique As String    Dim Flag As Long     Flag = 0    Dim currentValue As Integer    Dim prevValue As Integer        Set db = client.OpenDatabase("TEST.IMD")                ' Allow the field to be editable     Set table = db.TableDef        ' Get a RecordSet object for the Access database         Set Field = table.GetField("UNIQUE")    Set rs = db.RecordSet      field.Protected = FALSE        'get the value        rs.GetAt(activeRec)    Set rec = rs.ActiveRecord        vAnneeRole = rec.GetCharValueAt(1) ' colone ID        vDateMer= rec.GetCharValueAt(2)     ' colonne Date_Action        vNom=rec.GetCharValueAt(3)            ' colonne Nom        vAction= rec.GetCharValueAt(4)         ' colonne Action            Set Field = table.GetField("UNIQUE")    field.Protected = FALSE    rec.SetNumValue "UNIQUE", Flag                rs.SaveRecord rec            field.Protected = TRUEEnd Function