Copy/paste opacity problem

I´m having this weir issue with objects that have gradients with opacity.

If I drag to copy, it´s makes a perfect copy. But if I copy/paste the object it becomes solid. This applys copy/paste in the same document and if I try to copy/paste into a new document.

This problem came with the upgrade to Illustrator CS6.

Anyone?

Mac OSX 10.7.5

Adobe Illustrator 16.0.4

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