by Ian Youngs
BBC News Online entertainment staff
Glastonbury Festival organisers have urged fans not to turn up at the event site on Friday - the anniversary of the first festival in 1970.
Michael Eavis has organised the festival on his farm since 1970
Some fans thought another festival was taking place in 2003 after a poster for the original event appeared in this year's programme - giving the date but not the year.
So they followed the poster's instructions to send cheques for £1 per ticket to organiser Michael Eavis.
"You'll be waiting 'til the cows come home," a statement said.
The poster in this year's programme was a replica of that used for the "pop, folk and blues" festival held on Mr Eavis' farm in Somerset on 19 September 1970.
It promised a line-up including The Kinks plus "freaks and funny things", an ox roast and free milk.
The festival has grown into one of the world's biggest music events
About 20 people sent cheques to Mr Eavis after seeing it, requesting up to 10 tickets each - but their cheques were returned with a note saying "sorry for the confusion".
The festival website said: "Some people have understood this to be an event at Worthy Farm on the 19th September this year. Great idea, but it's not going to happen.
"To be totally clear, the advertisement was from the festival archives and there will be no event held at Worthy Farm this year on this date. Sorry."
The 1970 event was attended by 1,500 people who watched T-Rex headline after The Kinks pulled out.
It began one of the world's most legendary music events and the 112,500 tickets for this year's festival - still held on Mr Eavis' farm - sold out in 18 hours.
Organisers are now looking at ways to make ticket allocation more fair and beat touts - including an airline-style ticketless system, where fans would be given booking reference numbers.