Guy Luzon was not in the dugout for Charlton's match against Watford due to issues with his UK work permit.
Following his appointment on Tuesday evening, the club had expected the required paperwork to be finalised in time for the Head Coach to take his place in the dugout at Vicarage Road.
However, his work permit was not processed before the required deadline, according to a club spokesman.
First-Team coach Damian Matthew and Goalkeeping coach Ben Roberts were in temporary charge of the side that lost 5-0 in the Championship match.