Is the Femme Fatale Tour a flop? Britney Spears has been selling tickets to many of her concerts for as much as 50% off using the discount website Groupon, and even some of those deals haven't sold out.

The National Enquirer says that Spears is unaware that her ticket prices are being slashed. "Britney thinks everything is going great," an insider said. "She's clueless!"

The Enquirer isn't necessarily the most reliable source, and the idea that Brit doesn't know about the discounts doesn't seem to be true, since she once promoted half-price tickets to her shows on Twitter. Still, the Groupon deals must indicate that lots of tickets are going unsold.

A Live Nation spokesperson tried to put a positive spin on the Groupon deals, saying, "Offering a deal on Groupon is not a reflection of the quality or status or sales of a show" and adding that the promotions were part of a strategy regarding "segmented marketing and a way to reach new and additional consumers."

That statement notwithstanding, you don't see Lady Gaga or Taylor Swift concerts on Groupon. Slow ticket sales for the Femme Fatale aren't a huge surprise, considering that at some venues, the cheapest seats available were over $100. Britney has a hardcore fan base, but in this economy, those prices are steep.

Pollstar's mid-year tour report ranked the Femme Fatale tour in 55th place, grossing $6.2 million, but that was just from the first 10 shows. We'll have to wait for the year-end report to find out how successful the full tour is.

Watch the Britney Spears 'I Wanna Go' Video