Excluding bars with null value in a bar chart

[Anonymous]

I have created a bar chart and as you can see, School C of 2011 and School D of 2013 have null values. How can I exclude/ hide those two bars in the chart? However, school C and D of other years should continue to be displayed.

[Michiel_QV_Fan]

Not possible because of the use of more than 2 dimensions.