XYchart ScrollBars stack plots

hello ,
i am working on a XYchart , data are binded to a query and that changes with 2 dropdown selection.
work well on the first plot , but after new chart come it keeps all the previous and the new one , like in the screen shot :


i think this has somthing with the serie’s data source name, because when i change this one from a third dropdown it works well till i am updating new data with the same name