Thanks tsac - have done that and now when I send her my pin, it stays on the 'pending'.
Also I had my wife trying to add my sister on her BB and the same thing happened; it stays on pending.
But I do have other contacts that work OK; and the same contacts also work OK for my sister but for some strange reason my wife and I can't add my sister.
My sister is in Venezuela and my wife and I are in Australia. But as I said, we connect OK to other contacts in Venezuela and they connect OK to my sister - it's juts that I (and my wife) can't connect with her