PEOPLE ARE rolling up for the greatest show on Earth - but before the Edinburgh Fringe festival even begins, there are problems with tickets.

The Fringe, which starts on August 5, is the world's largest arts festival, with more than 28,000 performances and 1.5 million seats. Already, the Fringe box office has sold some 200,000 tickets.

But when the shows begin, producers are predicting double bookings and mix-ups because four of the major venues have introduced new ticket software this year. People have already noted system failures and shows falsely reported as full.

The Assembly Theatre, Pleasance, Gilded Balloon and the Underbelly are set to feature names such as Frank Skinner, Matthew Kelly, Les Dennis, Michelle McManus and Jerry Sadowitz. This year, they have teamed up to sell tickets for each other, with software called VIA.

But the Fringe, which acts as an agent to sell at least 30% of all tickets, is still running the old software system, WTS.

Managers at the four venues "release" a third of tickets to the Fringe, paying 6% of the ticket price. This year promoters have to check ticket sales on the two systems to find out if more need to be released to the Fringe or taken back.

Louise Chantal, theatre producer for the Assembly, said some performances of popular shows such as Havana Rumba have shown up as sold out at the Fringe, when she still had tickets.

"Now our ticketing system isn't live with the Fringe system," she said. "I have had a situation where no-one thought they could buy a ticket, as the Fringe had sold out of its allocation - but they could have. It isn't ideal and very annoying for someone who has a whole raft of shows."

Other promoters have reported "teething problems" with VIA, including a wrong number of tickets being issued.

Sheridan Humphreys, publicist for shows including The African Children's Choir, said: "Producers of more than one show at a single venue are finding things a bit long-winded. The venue must have a facility to see all figures at once - unless they are using an abacus."

Keiran Healey, marketing manager for C venues - the other large-scale programming Fringe venue - said they decided to use WTS because of training issues and early hitches. He predicted problems, particularly at the busiest times. "In any theatre production, on big nights, or at the end of the Fringe, there are inevitably tickets that aren't accounted for," he said. "It is down to humans co-ordinating two computer systems, and humans are not infallible."

Anthony Alderson, Pleasance director, said: "It is a terrifying thing to do to change systems when you have no way of testing it until you sell 1.5 million tickets."

Tony Davey of software firm Red61, who sold the Fringe venues the new VIA system, admitted: "It makes it a lot easier to have the same system for all. We are trying to get the Fringe on board. This year, it was too late."