Getting chart dimension on expression

[Anonymous]

Hello,

i have a pie chart with multiple alternative dimensions. I don't want to display null values on the graph, instead im showing them on the footer with the expression ='Datos nulos: '&num(-1*SUM(IsNull(CRITICIDAD))*100/sum(ACTIVA), '#0,#')&' %'

I want the null count to change when i select another dimension, is there a way to do it within the graph propieties? (without the use of variables)

Some function that returns the dimension a graph is taking would work nice, but I can't found it.

Thanks,

Roger