A number of Macworld readers posting in the Macworld Forum have expressed concerns that their e-tickets for MacExpo will be rejected when they go to the show next week.

MacExpo distributed an email containing the e-tickets on November 4. On opening the pdf attachment that contained the ticket a number of readers found that certain details were missing – specifically the barcode and reference number.

It has emerged that in order to see and print the ticket in its entirety it is necessary to open the attachment in Adobe Acrobat. Some reader's Macs automatically open PDFs in Apple's Preview application.

Because the e-ticket was created in Acrobat it is necessary to open it in that application, MacExpo warns.

Dismissing the concerns, a MacExpo representative said: "The e-ticket letters for MacExpo were created in Adobe Acrobat to facilitate the data merge, as you have discovered the merge does not work if you subsequently view the pdf in Preview.

"Whilst this is unfortunate we have found everyone that has encountered the problem also has Adobe Acrobat and has been able to open the pdf once informed."

He added that the event organiser had added instructions to the MacExpo Web site that emphasise that the email letter sent with the tickets states it was created in Acrobat.

"Apologies for any inconvenience but the pdf has to integrate with a unique registration system that we are developing for this and other events and Preview compatibility after the merge could not be added at this stage," he explained.

The MacExpo organisers now plan to send out a subsequent email to all registrants in which they will refer to the problem.

"The few queries we have had have all been rectified when people use Adobe Acrobat and as it ships with all Macs we have not had anyone unable to view it correctly," claimed the spokesperson.