Frustrated boss Jimmy Floyd Hasselbaink believes a lack of stability and consistency is the root cause of the Cobblers' current run of poor form.
Town made it five matches without a win or a goal as they were beaten 2-0 at Portsmouth in Saturday's Checkatrade Trophy second round clash.
A goal in each half from Gareth Evans and Stuart O'Keefe secured the win for Pompey, while the Cobblers again drew a blank.
The team hasn't scored since Chris Long's first-half strike in the 2-1 win at Oxford United on November 11, and although they did create some chances at Fratton Park, they couldn't take them.
Town had good spells in the game, but in the end were deservedly beaten, and Hasselbaink knows his players need to start performing well more consistently.
"It is always frustrating to lose, but the thing is we need to find some good stability as we are too up and down, and I think the better team won today," said Hasselbaink.
"Today, in patches we played alright, but in patches not so well, and we need to really work at good stability.
"That will give us a platform and the possibility to win matches."
Town did have two big chances to score in the game came at 0-0 and 1-0, with Pompey goalkeeper Luke McGee denying Long and Ash Taylor, the latter an excellent stop from a header.
Annoyingly for Hasselbaink, Pompey's opener was scored following a Cobblers attacking corner after Long's shot was saved, and he says that outlined his team's lack of 'know-how'.
"We should have handled that break in the middle of the park," said the Town boss. "But that is the immaturity we have, and the lack of know-how.
"I can't fault the players for trying and being honest and doing their best, but in those moments we need a bit more know-how."
A big plus from the trip to the south coast was the return to playing action of Sam Hoskins, who got through 64 minutes before being replaced by Dean Bowditch.
The attacker hasn't featured since injuring a hamstring against Scunthorpe on November 4, and he looked sharp throughout.
"A plus point was that we have Sam back, and on purpose I gave him 60 minutes," said Hasselbaink.
"Could I have given him a little bit more? Yes, but he is so important for us that I don't really want to risk that.
"So him playing for 60 minutes was good, he will now get another week of good training, and hopefully he will be okay for Saturday."
Town travel to Oldham Athletic in Sky Bet League One next weekend, and Hasselbaink is also confident he will be able to call on striker Long, despite him being taken off at half-time with an injury.
"Chris rolled his ankle, but I don't think it is serious," said the Town manager. "We just didn't want to take a chance on him."