in your expression you are comparing the value of sum(pretax)/vtotal... with the string '02.00%' and i don't think they are saved like that in your schema right? the 2.00% is probably a number formatting in the chart that you are using, so check first what does this expression returns sum([Pre-Tax Value])/VTotalPreTaxValues) and then add the filter.
maybe it should be sum([Pre-Tax Value])/VTotalPreTaxValues) > 0.2
