Как через ADO узнать является ли текущее поле Primery Key?

Function FieldIsKeyPrimary(strNameField As String, strNameTable As String) As Boolean
On Error Resume Next
    Dim cat As New ADOX.Catalog
    Dim objKey As ADOX.Key
    Dim objColumn As ADOX.Column

    cat.ActiveConnection = CurrentProject.Connection

    For Each objKey In cat.Tables(strNameTable).Keys
        If Err <> 0 Then Exit Function
        If objKey.Type = adKeyPrimary Then
            For Each objColumn In objKey.Columns
                If objColumn.Name = strNameField Then
                    FieldIsKeyPrimary = True
                    Exit For
                End If
            Next
        End If
        If FieldIsKeyPrimary Then Exit For
    Next
End Function