Dead reckoning recipe doesn't work

I'm trying to create the dead reckoning jewel that gives the 15 mages, not the one with chaos damage.

I have 4 sage wands (normal, magic, rare, unique)

I have the 20 quality summon skeleton gem.

When I add the gem, instead of creating the jewel it just offers me a bauble for the 20 quality.

Any thoughts?

Are you sure the wand base type is the same for all four wands?

To add to what has already been said so far, skeleton mages are still available through the transfigured gem "Summon Skeletons of Mages", technically opening up a jewel slot for skeleton mage builds.