Display rules on custom graphs

[Benvolio]

I have a custom graph which is basically two bar charts overlaid. I want a display rules which effects only one of the charts, but currently the rules consistently effect both bar charts. I have successfully applied the rules to one chart accidentally before so I know it can be done...
Thanks in advance, Ben.

[Madelyn_SAS]

What roles are available, and are you applying the display rule to a Shared Role?

[Benvolio]

Hi, yes there is only one Role that is shared between both.
Does this mean I need two different roles?
Will the bars be perfectly overlaid if the roles are seperate?