Bolton manager Owen Coyle said West Brom's equaliser in their 1-1 draw should not have been allowed.
Coyle claimed Baggies striker Peter Odemwingie should have been flagged offside before he crossed for James Morrison to level the match.
"The disappointment for me is that with the goal they scored, Odemwingie is clearly offside when the ball is played through," Coyle said.
"We paid a heavy price for a decision that should have been stopped."
After an uneventful first half, Bolton took the lead through Johan Elmander and could have gone 2-0 in front when Martin Petrov fired wastefully wide when through on goal.
But Morrison's goal 12 minutes from time consigned the Trotters to their fifth draw in seven league games this season, with their only victory coming at West Ham on 21 August.
Coyle continued: "I think he (match official Peter Walton) is a very good referee and ultimately that decision is not for the referee - it is for his assistant.
"I will go now and ask the question of the assistant referee why he didn't flag, but I don't want that to take away from what was a terrific game.
"Ultimately it has cost a goal and you don't know how things would have panned out if it wasn't given at that point, but what I do know is that we looked a very good side for large periods of that game."
West Brom boss Roberto Di Matteo said he had not seen a replay of the Odemwingie incident but declared himself satisfied with a point which stretched his side's unbeaten home run to 14 league games and kept them in sixth place.
Comebacks show our strength - Di Matteo
"I'm very pleased that after we went behind, we managed to get the goal and draw the game.
"Bolton are very organised and make it very difficult for the opposition. The second half was much more open than the first half and both sides had chances but I think it was a fair result.
"Considering that some of our players were not in the best form today, we still came back from 1-0 down and could have won it at the end - although I don't think we deserved to, to be honest."
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