Invulnerable Armor - invalid recipe?

[Say10]

Invulnerable Armor: Damage reduction 10/magic
Requires: Caster level 18, Craft Magic Arms and Armor feat
- Any armor
- Radiant Fire Essence
- Blue diamond
Cast stoneskin on a magic workbench containing the above

All I get is This is not a valid recipe.. Anyone know why? This is the recipe from Deflections and Dispellings book...

[GoldDragon]

Invulnerable armor itself is bugged.

You COULD try reporting it on the Official forums or sending a report to OE...

[Loki[D.d.G]]

It has been bugged for some time. If I recall correctly, another bugged recipe is the Flaming Burst. Never did craft much, so I wouldn't know for sure.