Adams saw his side surrender a two-goal lead at half-time to lose 3-2 at home to Swindon on Saturday.
He said: "It's very disappointing because the goals we are conceding are criminal. We can't keep defending like this and expect to win games of football.
"We will have to find a solution because our failings are certainly not being caused by a lack of practice. We work on all aspects of our defending from the back four to the line in front, and we will have to keep on working at it until something clicks.
"It was important to stay tight at the start of the second-half, but we've conceded early and that has put us on the back foot straight away.
"We've also got punished by some good players. Luongo (Massimo) has run the show in the second-half and we've also not dealt with Pritchard and Ranger. We didn't get close to them and if you don't get close to good players you pay the penalty.
"I've got some players who have been out of the picture for a while and they could well come back into it when we play Colchester on Tuesday."
Swindon dominated much of the early play but Vale took the lead with their first serious attack in the 20th minute.
Jennison Myrie-Williams beat Darren Ward to deliver a low cross from the right and Doug Loft's right-foot shot on the turn from six yards out squeezed inside the near post.
The Robins' general play continued to impress as they forced eight first-half corners, but Tom Pope's first goal in six games left them two down at the break.
The unmarked Pope pounced on some dreadful defending as his left-foot shot from 10 yards squirmed just inside Wes Foderingham's left-hand post in the 42nd minute.
The visitors were back in the contest six minutes after the interval when Alex Pritchard's cross from the right was headed into the roof of the net by Ranger at the far post.
Swindon then struck the woodwork twice as Smith's shot rattled a post before Ranger's effort clipped the crossbar.
But Mark Cooper's men almost inevitably drew level when man-of-the-match Pritchard curled a 25-yard free-kick into the top right-hand corner of the net with a sumptuous right-foot shot after 65 minutes.
And a ragged Vale outfit could have no complaints four minutes later when Smith's low cross from the right was bundled in at the far post by Nathan Byrne.