Nigel Pearson's men needed a 90th-minute Chris Wood winner last week against Yeovil Town and, despite the boost of victory over title rivals Burnley at the weekend, required a late goal again at the DW Stadium.
After Ivan Ramis opened the scoring, Andy King levelled just four minutes before the interval. Rob Kiernan then restored the hosts' lead before Dean Hammond headed home with three minutes remaining to salvage a draw.
Elsewhere in the Championship there was a six-goal thriller at Ewood Park as Blackburn Rovers and Brighton and Hove Albion shared the points following three goals in the final 11 minutes.
It was a case of missed opportunities at the top of League One as both leaders Wolves and second-placed Brentford were held to goalless draws.
While Brentford came unstuck against play-off hopefuls Sheffield United, Wolves surprisingly failed to beat Stevenage, who climbed off the foot of the table courtesy of the point they gained.
Thanks to Coventry City's 0-0 draw with Bradford City, the only goals in England's third tier on Tuesday came at Vale Park.
Strikes from Billy Knott and Doug Loft helped Port Vale come from a goal down to edge Crawley Town in a game that saw both sides finish with 10 men.
