Wednesday have failed to keep a clean sheet since February 10, conceding nine goals in their last seven outings.
A number of the Championship club’s top players are missing due to injury, including centre-back Tom Lees and Sam Hutchinson.
But Carvalhal refuses to blame their long list of absentees for their dip in form, insisting the team must cut out the defensive lapses in concentration.
“We are trying to score goals all the time but we must correct the mistakes that we are making and try to be better in the next game,” he told The Star.
“That is the most important thing.”
Wednesday will have to make one enforced change to their backline when they entertain play-off rivals Reading on Friday.
Vincent Sasso will begin his three-match suspension following his red card at Aston Villa.
Carvalhal hopes Lees (knee) and Glenn Loovens, who was taken off at Aston Villa after picking up a knock, will be passed fit to play.
He said: “Let’s see during the week. Tom started training with the team on Friday. He didn’t feel any reaction. Glenn felt a problem that came from the back. We have good expectations that he will recover for the next game.”
Despite a mini wobble, Reading remain fifth in the table and boss Jaap Stam is confident they will secure a top-six finish.
Stam said: “We are not thinking about losing and possibly being out of the top six.
“We need to be ruthless in defence and in attack.”