Scatter plots: how to size by a variable within trellises

[Hannah Elzinga]

I am creating a scatter plot that is trellied into four different sections. I want to size the scatter plot dots by the same variable withineach individual trellis but only to the data within that trellis. Currently when I use the "size by" function, Spotfire applies the setting to the data across all four trellised sections. How to I apply the "size by" function to each trellis individually

Thanks!