ITV boss Michael Grade: 'It shouldn't have happened'
The Football Association (FA) is demanding "a full explanation" into how viewers missed a crucial FA Cup goal due to a technical hitch.
Everton's winning strike in extra time happened as ITV1's coverage abruptly went to an advert break.
ITV boss Michael Grade has said the glitch, which has prompted 1,000 complaints, was "inexcusable".
An automated system for screening adverts was still in place during the extended Liverpool v Everton match.
It is used when schedules are running normally, and fails to take overruns into account.
Viewers in some regions were still able to see substitute Dan Gosling's goal, but others returned to the coverage during the players' celebrations.
Dan Gosling celebrates after netting the crucial goal for Everton
"Technically it came at a particularly bad time for us," said host Steve Rider before saying sorry.
Grade said: "As a football fan myself, I was glued to the match and was as disappointed as anyone to miss the goal."
He added: "We have years of experience in dealing with the changes in ad break patterns when games go into extra time and sometimes penalties.
"This we have done faultlessly through the Champions League, World Cup and European Championships.
"We are awaiting the results of our technical inquiry so we can put in place stringent and immediate procedures to address this," he added.
In a statement, ITV called the occurrence an "unprecedented transmission error".
But the FA has called for a fuller explanation, saying the mistake was "very disappointing".
"It is important that lessons are learned and that this does not happen again," the FA said in a statement on its website.
Everton fan Robbie Hall said: "I was watching on Freeview and once the adverts got under way we had no idea what was going on.
"After about 10 seconds the game returned just as Gosling scored. I saw the goal live but it was a mess."
Paul Snowdon from Merseyside said: "ITV needs to start taking its football seriously. This should never have happened."