A fifth consecutive match without scoring, and a fourth defeat in five, saw Posh fall five points adrift of safety as rivals Reading and Hull City fought out a 1-1 draw.
It was an improved first half performance from Posh, but they were unable to go into the break ahead, despite having the better of the match.
Jorge Grant and Siriki Dembele missed the best chances for post either side of the break and their hearts were broken by two late goals, in the 72nd and 84th minutes by James Garner and Ryan Yates.
Ferguson said: “We played well for large parts. We had two very good chances in the game at 0-0 and we have to take one of them. We have to find a way of getting ahead away from home and we also have to find the ability to, if we’re not going to score, make sure we got a 0-0. Those things are letting us down badly at the moment.
“In any game of football, they are two very, very good chances. We have to find a way of getting one of those in. I don’t know what Jorge is doing, just put your foot through it and Dembele has hit the outside of the post. It has to go in. They were the best two clear chances of the game.
“For large parts of the first half, we were dominant but, when you are dominant in a game like that, you have to go ahead and at the moment, we are simply not doing it. They were booed them off at half time as we had done every part of our job but score. We had to be ahead.
“We knew there would be periods we would come under the cosh, but you have to be strong. We have to do more to stop the ball going into the box for the first. It could be argued I keep saying the same things, but the same things keep happening.”
Posh’s fifth blank in a row was the first time the club has done so in 19 years, a statistic that has bemused Ferguson.
He added: “I can’t believe it, especially with the way I’m setting them up. I still believe in the players and the quality they’ve got but at the moment, we’re not finding that final bit to get goals and it’s really disappointing. We’re setting up in different ways, we’re trying all sorts of formations. We went with the diamond today, it worked, we were causing them all kinds of problems, but this keeps happening.”