Aşağıdaki kodları dener misiniz..
Private Sub addNew()
Dim insSQL As String, myName As String, myPrtc As String
myName = Nz(Me.HastaAdi, "")
myPrtc = Nz(Me.Protokol, "")
If myName <> "" And myPrtc <> "" Then
insSQL = "INSERT INTO Kisiler (HastaAdi, Protokol) VALUES ('" & myName & "', '" & myPrtc & "')"
CurrentDb.Execute insSQL
End If
End Sub

Private Sub HastaAdi_AfterUpdate()
Dim i As Integer
i = DCount("*", "Kisiler", "[Protokol]='" & Me.Protokol & "'")
If i = 0 Then
Call addNew
End If
End Sub

Private Sub Protokol_AfterUpdate()
Dim myName As String
myName = Nz(DLookup("[HastaAdi]", "Kisiler", "[Protokol]='" & Me.Protokol & "'"), "")
If myName <> "" Then
Me.HastaAdi = Dlookup ("[HastaAdi]", "Kisiler", "[Protokol]='" & Me.Protokol & "'")
Else
Call addNew
End If
End Sub