Actor Harry Shearer, a regular on US cartoon series The Simpsons, has been forced to cancel an appearance on a Radio 4 comedy show, the BBC has said.
Shearer voices Ned Flanders on The Simpsons, among other characters
The 62-year-old had to pull out of the recording of Not Today Thank You due to "a problem with his work permit".
Dead Ringers star Mark Perry took his role as Nostrils, a self-centred tenant living in the house of a faded radio host played by Five Live's Brian Hayes.
"We are doing all we can to resolve the problem," said a BBC spokeswoman.
Shearer had been scheduled to appear at Monday's double-episode recording of Not Today Thank You at London's Drill Hall Arts Centre.
According to the BBC, he is expected to star in the remaining four instalments of the Radio 4 programme, to be broadcast next month.
In the show, Brian Hayes plays Brian Hughes, a washed-up radio presenter who tries to broadcast his show from his grandmother's basement.
The cast also includes Sheridan Smith, from BBC Three sitcom Two Pints of Lager and a Packet of Crisps.
Shearer voices a number of characters on The Simpsons, including Montgomery Burns, Waylon Smithers, Ned Flanders and Principal Skinner.
His other roles include rock star Derek Smalls in cult 1984 comedy This Is Spinal Tap.