faced this issue recently ...had booked a ticket using new irctc ( next generation website) ...but when i was trying to cancel the same ticket , the older site kept on opening , and to my surprise that didnt show the ticket i booked in history and hence was unable to cancel.
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then i tried nget.irctc.co.in and it straightaway took me to the new interface and was able to cancel the ticket ...but wonder why the old and new site are not in sync..secondly one should try nget.irctc.co.in instead of irctc.co.in..