The Whites played out a goalless draw with Charlton at The Valley in the Championship.
Dallas, who joined the West Yorkshire outfit from Championship rivals Brentford in the summer transfer window, believes that failure to retain composure in front of goal and bad luck cost them two points.
“You need a bit of composure in front of goal and you need that luck as well,” Dallas told Leeds’ official website. “Today we didn’t have that luck. You get those games throughout the season.
“It feels a little bit like a defeat because the lads knew we needed to follow up last week with another win, unfortunately we just couldn’t do that.”
Over the course of the 90 minutes at The Valley, visitors Leeds had 56% of the possession, took 18 shots of which just three were on target, and earned eight corners.
The performance of Steve Evans’s side against Charlton in the first half was disappointing, but the players stepped up their game in the second 45 minutes.
The West Yorkshire outfit are 18th in the Championship table at the moment with 23 points from 20 matches, seven points above the relegation zone.
Leeds will return to action on Thursday evening when they take on Wolverhampton Wanderers away from home at Molineux in the league.