I checked, and the +2 ring of protection does actually have a +2 deflection AC modifier against it.
In all likelihood, you just need to make sure it's equipped. When you add new items to a character/creature, they aren't automatically equipped. You equip them in the items list using the drop down list for "Active".
The 3 options are:
- Equipped: where the effects of an item are in play, and their weight counts against your total weight carried.
- Carried: where the effects are not in play, but the weight is counted.
- Stored: where you own the item, but have it stashed away somewhere, and the weight isn't factored into what you're currently carrying.
Other than that, if you've been doing some playing around with your character, you may want to try a "ReCalculate".
At any time, you can bring up the "Modifiers" window for the selected character. This gives you the full breakdown of all the modifiers (from equipped items, race abilities, class features, feats etc).
The "AC" is normally right at the top, and if your +2 ring is equipped, you should be clearly able to see that there is an AC modifier for a +2 ring of protection giving you a non-stacking deflection bonus of 2.
