Britney cancels German gig - technical or ticket difficulties?

Following all those rumours that Christina Aguilera actually cancelled her US tour because of poor ticket sales (look, she's got a throat infection, OK), the Sun reckons Britney has cancelled a German gig for the same reason - ie no one wanted to come. Although the official reason for the cancellation of the Reisa gig was 'technical difficulties', the tabloid says Britney refused to perform in front of so many empty seats - they say just 3,000 of the 12,000 tickets available were sold.