Coupling UK vs. US
In 2000, Steven Moffat's cleverly-written comedy Coupling first aired on BBC2. The show had a 4-series run and was extremely well-received. It tested so well, in fact, that American television network NBC attempted a remake of Coupling in 2003. The US version failed spectacularly despite a significant cult following of the British version in the States. At one point, BBC America aired two episodes of Coupling UK every night. The American Coupling used scripts that were nearly word-for-word to its UK counterpart, so why did it fail to capture an audience?
A lot of critics blamed the casting choices for the show's failure, saying that the US cast was amateurish by comparison. While the UK version's cast was really a stellar ensemble of talented comedians, the US cast had a lot with which to compete.