Professional Game Match Officials Limited have launched an investigation into referee Mick Russell's failure to send off Sheffield Wednesday's Jeremy Helan in Saturday's derby with Huddersfield.
Russell showed Helan a second yellow card in the 26th minute of the 0-0 draw against Huddersfield but failed to produce a red card.
The referee booked the midfielder for a foul on Huddersfield's Adam Hammill, but did not realise he had already booked him for diving earlier in the game.
A statement from the Professional Game Match Officials Limited (PGMOL) said:
"The Professional Game Match Officials Limited are to conduct an investigation into an incident that took place in the Huddersfield Town v Sheffield Wednesday game in the npower Championship on Saturday.
"In the eighth minute of the match Mick Russell, the referee, stopped play when Jeremy Helan was adjudged to have simulated an offence inside the Huddersfield penalty area.
"However, it appears that instead of Helan (number 24) receiving a caution, one was given instead for Michail Antonio (number 7).
"At this point the referee recorded the name and number of Antonio in his notebook and advised the fourth official over the communication system that
Antonio, number seven, had been cautioned.
"In the 25th minute Helan was cautioned following a foul challenge. As the referee had not previously recorded his name he did not issue a red card for
receiving a second caution in the same game.
"The official has subsequently admitted making a genuine error and PGMOL need to determine why this arose and what sanction, if any, should be
administered to the match officials."