David Hopkin was left ruing missed opportunities following City's Sky Bet League One loss to Charlton Athletic.
The Bantams head coach saw his side concede goals either side of the interval, despite the hosts creating several chances.
Visitors Charlton took the lead early in the opening period and, despite a lengthy period of second-half pressure from City, the London club sealed their success late on.
Hopkin said: "Charlton broke into our half on the back of one of our early chances and we gifted them an easy goal, so the result was difficult to take.
"We put some good crosses into the box during the opening minutes and should have scored from at least one of them.
"We again can take plenty of positives. All the things we have worked on in training came off. In the areas we have focused on, improvements were made.
"But it ultimately comes down to individual errors and it isn't good enough at the moment. We have to keep it tight at the back and it has cost us for the second week running.
"We were on top for most of the second half, so it was frustrating that we didn't take our chances. You have to score when you have so much possession.
"When you don't score - and you are pushing - you leave yourself vulnerable to conceding a second and that is what happened.
Hopkin hailed the efforts of man of the match Jim O'Brien and youngster Lewis O'Brien, who both appeared for the first time at the Northern Commercials Stadium.
Jim penned an initial four-month deal with the club on Thursday evening, following a successful trial with the Bantams, while Lewis appeared as a substitute - seven days prior - at Blackpool.
Jim was fantastic and I knew we would get a great performance from him," added City boss Hopkin.
"He was lively in the dressing room and came in at the start of the week with plenty of experience and enthusiasm.
"He is a great character and we are going to need people like Jim. Him and young Lewis O'Brien were superb.
"For a 19-year-old to come and debut in front of a big home crowd brings a lot of pressure and the supporters really took to him.
The Bantams return to Sky Bet League One action on Saturday, travelling to face Doncaster.
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