Side effect when settting PropertyDefaults for Charting.Grid to Enabled = false

When setting the PropertyDefaults for Charting.Grid to Enabled = false, it will lead to Charting.TickMark Enabled set to false as well.
An additional type check might do the trick:
let internal applyDefaults (chartType:SeriesChartType, target:'a, targetParentType:Type option, targetType:Type, property:PropertyInfo) =
....
(propDefault.ParentType |> Option.forall (fun parentType -> parentType = targetType)) &&
....

PS: This is my first command at all. I hope it is properly stated...Plus many thanks for providing such a great library...