Dear,
I suppose you created an analytical drvier ( called "date" ) and use it inside cockpit.
You've configured the data set in the right way, linking the analytical driver to the data set parameter's.
So, in this way the chart you've just created use the data set replacing the parameter selected in the analytical driver.
Can you verify if the data shown by the chart are correct, and try to change the analytical driver "date" and verify if the chart will change.
Best regards
Angelo