you can graph formulae using the above method as well. i.e. create a new formula like Val({field}) and then use that formula as the Show Value.
another way you can do this is:
1) change the select back to "On Change Of"
2) use a distinct value as the On Change Of which ensures that there's a bar for each record...i.e. a unique row identifier from the database
3) in the Show Value, use your formula, but change the summary type from Sum (the default) to Max...although this step shouldn't matter if you do in fact have a unique identifier for each record as the On Change Of