You're probably not doing anything wrong, because I believe rollable tables only have description and weight...the example above is to help bridge the gap between the table in the book and the rollable table. So, you could create a table rollable using the Sub-effect and the Weight as the Description and the Weight. The Wound space is for tracking wounds and has nothing to do with the rollable table. Instead, what you would want to do is on the Configuration tab (toward the bottom) click that you're using Gritty Damage and provide the name of the rollable table you set up. That way, when you roll damage, you'll get a button to roll the gritty damage table. Here's how I have my table set up: Here's the Configuration Tab with the Gritty Damage checked (under Rules Modifications): Here's what the damage output looks like when I click roll damage (from the character sheet): And here's what the output looks like when you click the Roll Injury button: I hope this helps. :)
