scroll graph ...how to eliminate #REF

Hello

managed to put together a scrolling graph, where quota is shown at a stand still vs. sales ppl actuals.

i have highlighted in "yellow" where the scroll data is triggered from, however, i cant seem to remove the #REF that is show on the graph?
-if u scroll to the very right of the graph, it will show a #REF error.

can someone pls help me remove those; ive been at this for the past day+. thx you so much!!!!!