Edinburgh Pride is on that date as well - maybe there were too many events on one day that were going for a similar market, resulting in low ticket sales for this? Whatever happened it's a real shame
I also noticed that because they were announced later than the other headliners, Sugababes were absolutely nowhere to be seen on most of the print and public advertising (the ones on Glasgow subway trains STILL have the original lineup on them for example). Could that have hurt sales a little bit as well?