Paul Benson's loan move from Charlton to Swindon has fallen through.
Benson, 32, looked set to sign for Bradford on the final day of the loan window but the move collapsed and the Robins swooped for the striker.
But the Football League said documents were not received until after the 1700 GMT deadline on Thursday.
Swindon chairman Jeremy Wray has confirmed the club will now try and bring the forward to the County Ground when the window re-opens in January.
Wray told the club website: "We held lengthy discussions with the Football League trying to persuade them to afford us a limited degree of leeway but rules are rules and in the final analysis we sadly fell outside of them and, therefore, have to adhere to the Football League ruling.
"It is very disappointing for all concerned but hopefully we can revisit the Paul Benson registration in January 2012."
Benson signed for Charlton for an undisclosed fee from Dagenham & Redbridge in August 2010 and scored 10 goals in 43 appearances last season.
He attracted interest from Notts County in the summer but the deal, thought to be worth around £150,000, collapsed after he failed to agree terms.
This season, he has played just three games for the Addicks.