Task: Question Answering
Input (English): Passage: Although Moran's transition as The Wiggles' lead singer was "smooth" for the young children of their audience, it was more difficult for their parents.  Moran said that "most children understood".  Field reported that by the group's 20th anniversary in 2011, due to the ever-changing nature of their audience, most of their young fans were unfamiliar with Page.  Cook stated that Moran's transition was challenging for the group because since he replaced their lead singer, it changed their sound.  Fatt characterised Moran's singing style as more operatic, so they chose different keys to sing and perform.  The Wiggles never publicly disclosed how much Moran was paid, but it was reported that he earned $200,000 per year.  Moran was featured in his first DVD and CD as a member of the group in early 2008, and a sixth season of The Wiggles' television series featuring Moran was filmed and began airing in Australia.At the end of 2007, The Wiggles donated their complete back catalogue of 27 master tapes to Australia's National Film and Sound Archive. Their business ventures during these years included opening up "Wiggles World" sections in theme parks in North America and the Arab World, internet offerings, the creation of new television shows, and a five-year-long partnership with the digital cable channel Sprout in 2009.  In December 2010, Cinemalive beamed a Wiggles concert live from Acer Arena into movie theatres all over Australia, for children and their families unable to attend their shows.In early July 2011, founding member Fatt developed arrhythmia and underwent "urgent but routine" heart surgery, when he was fitted with a pacemaker after feeling unwell for several weeks and blacking out.  He missed the group's US tour as a result, after not missing a show in 20 years.  Also in mid-2011, The Wiggles celebrated their 20th anniversary with circus-themed shows and performances throughout Australia and the outback in a circus tent, as well as a "physically grueling" birthday-themed tour of 90 shows throughout Australia, which Paul Field called "one of the biggest of their careers".  Sydney's Powerhouse Museum commemorated the group's anniversary with an exhibit that displayed Wiggles memorabilia.In 2011, the worldwide financial crisis hit the group, and they recorded their first drop in revenues in 10 years, at approximately $2.5 million, a total decrease of 28 percent.  Royalties partially offset the difference between their 2010 and 2011 revenues.  Their managing director Mike Conway called 2011 their toughest year financially.  For the first time, they had negative equity, with more liabilities than assets, and the owners had to provide the funds for them to continue operations.  Conway stated that their losses were due to less touring time in the US, difficulties in placing their DVDs in Walmart, and their required investment in a new digital platform. 
Question: What three circumstances made 2011 the toughest financially for The Wiggles?
Output (English): difficulties in placing their DVDs in Walmart.