I just crafted a Magic Mirror and a Black Pearl Ring, but when place it in the Mirror and press the lvl 30 Enchants it does nothing.

The mirror itself works since i could enchant a Blood Sword or Diamond Sword/Armor.
IS there something i am overlooking with the rings/bracelets/amulets?

In the 1.7 version you don't enchant the items directly. At least it's not intended for you to. You instead enchant the pearls, either when you are crafting it, or afterwards. If you enchant them after, you need to place the enchanted pearl with the ring, and then a few more hits, and you might get the enchantment on to the ring.