It comes amid continuing disagreement between the DUP and Sinn Féin over the use of the grounds.The aviation events, which were scheduled to take place on the weekend of 23 August, attract thousands of people each year.Chairman of the charity Ray Burrows told UTV they have been preparing since last October for what they hoped would be their biggest open days ever - but have now had to cancel because they just didn't get the approval they needed from the Office of the First and deputy First Minister in time.He said: "I don't think there's words to describe how frustrated and disgusted I am. There is no reason why an education charity should be held to ransom for some decision that they cannot take."This would be our third or fourth year at the Maze site and in years past we have always got permission to hold the event, so we had no reason to suspect this year would be any different.We held off taking this decision as long as possible, but there obviously comes a time when it is impossible to continue - sadly, we have reached that point in time.Ray Burrows"The success of the event last year was evident so we went this year for a double day and we kept on asking throughout the year if we had got permission and no-one could say yes.CHAR(13) + CHAR(10) CHAR(13) + CHAR(10)"The whole UAS committee are devastated."Jeffrey Donaldson of the DUP said his party leader, First Minister Peter Robinson, has given his approval for the events but claimed the deputy First Minister has said no.He said Sinn Féin's Martin McGuinness is refusing after Peter Robinson withdrew his support for a peace centre at the Maze, near Lisburn, last year.The incident caused problems between Northern Ireland's two largest parties.Mr Donaldson said: "The First Minister has approved these open days but sadly the deputy First Minister has said no on the basis that he will only approve the open days when the former prison buildings at the Maze site are reopened for business so I'm afraid there's politics being played here."I think it's very sad that the Ulster Aviation Society is being used this way as a political football."Caitríona Ruane of Sinn Féin said there cannot be an à la carte approach to the development of the site and accused the DUP of reneging on agreements.She explained: "What Sinn Féin has said is that we want to see the development of this site and the DUP know what they have to do - they just need to sit down with us and work through this and we can do that, but they are refusing to do that."We have agreements but the DUP has reneged on those agreements."