I have this ring that says it will summon a goblin and will help picked up normal item. Once it picked 14 normal item, it will gives me a rare item with a chance for a legendary item. I am sure the goblin picked up more than 14 normal item already but why it did not gives me even a rare item? anyone facing this?

Puzzle Ring http://us.battle.net/d3/en/item/puzzle-ring
Summon a treasure goblin who picks up normal-quality items for you.
After picking up 12–16 items, he drops a rare item(yellow) with a chance for a legendary.
UPDATE:
BUG
Item count resets :-
1. when switching acts
2. upon player death even when within acts
3. when leaving the game
4. prevents you from getting more legs since it is counting? < Unconfirmed.

Even though  "Summon a treasure goblin who picks up normal-quality items for YOU", it is not the case when the count reset.
Players will once lose all white items without compensation thus better to pick up the white items YOURSELF before it does, for salvaging it and crafting.
More details here >> http://us.battle.net/d3/en/forum/topic/11914401365?page=1

Bugs have been patched.

All I can say is you didn't notice when the bugger drops the rare. Most of the time you only notice leg as the distinct piang sound...

No counter bro..

But it now correctly drops an item after collecting x amount of whites..irrespective if you cross acts/ die/quit and so on..