Castleford Tigers have been fined £500 over a mix-up which meant they ended up playing their televised clash with Huddersfield in a borrowed strip.
Both clubs arrived for the game at The Shay with similar reserve kits, leading to Cas playing in Halifax shirts.
A Rugby Football League investigation ruled the Tigers breached operational rules by failing to follow a directive telling them to wear their main strip.
Castleford said they disagreed with the decision but would not appeal.
Chief executive Richard Wright said: "I'm personally very disappointed by this outcome and disagree with the decision.
"However, it would not be viable both financially and in terms of time and effort for the club to appeal."