Calculated Fields are not filters. What you are doing there is just setting values to zero, but the data points (the records) are still there, hence they show up in legend.
What you want is to go in the Data tab on the ribbon, click "Edit filter", and set a filter to exclude the stuff you don't need. If that doesn't work, your filter is not set properly or you have records that match the filter and you don't realize it (or we have a bug, which is always possible, but the point is: what you want is filters, not calculated fields).
Can you try that and then post your filters if it doesn't work?