Hi
My father has visitor visa valid from 2004 to 2014. He visted US in 2004(stayed 4 months) and 2009 (stayed less than 6 months). He planned his third trip for 3 months. Yesterday(8/29/2011) he was flying from from HYD.India and connecting US bound flight from London.In london US officers didn't allow him to board plane reason they told is his visa was cancelled and they said not valid anymore.He had to fly back from London. We do not know exatly what happend and he never overstayed in US in his previous visits. Only new thing is he is carrying two passports. Old and new.
Visa stamped in old passport. Visa paper is also clear no damage at all.
Can you please advise me,what really happend with his visa and advise me what options I have now? Please let me know.

Thanks
Vara