Liddell again left out top scorer Adam Le Fondre and saw the Millers pay for individual errors in his first home match in caretaker charge.
But after winning 6-0 at Lincoln last Friday, the gaffer insisted the race for promotion will go to the end of the season and refused to be downbeat.
He told the press: "It was disappointing to lose. I didn't get carried away when we won 6-0 and I am not going to be too negative after the 3-1 loss tonight.
"We worked hard but just made too many mistakes and that is what cost us in the end. This is no disrespect to any of our lads or anyone playing in League Two, but they all make mistakes. The players who don't make mistakes are playing in the Premier League.
"I won't have a go at the players for their effort because they worked really hard tonight. We have said we are not going to be negative on mistakes and we are not going to change that but obviously if we can eradicate them then we are going to be a better team."
Liddell was asked about Alfie, who came on and scored the consolation goal, being left out once again and he added: "I don't worry at all about Alfie's ability in front of goal.
"He has taken being left out of the team well, as have all of the players who have been left out. We have a big squad and they all will be used because it is going to go down to the wire."