Custom serie Viewport always empty

Hi, I'm trying to create a custom serie using as example https://www.infragistics.com/samples/wpf/data-chart/custom-series . I'm using as base class "HorizontalAnchoredCategorySeries" because I need to have a CategoryXAxis and the idea is coexist with others CategorySeries. The thing is when I try to render the serie the Viewport that I'm getting is being always empty.

In a big picture it is attached my class

I would appreciate any kind of help

Thank you in advance