Despite dominating the game until 43 minutes, Town left Adams Park empty handed and another blank sheet on the road. With Michael Reddy becoming the third Mariner this season to miss a penalty.
Slade bemoaned the Mariners luck with Wycombe's opener coming whilst Ashley Sestanovich was off the pitch injured.
"For the second time this season we've conceded from a set play - when we've had ten players on the pitch. It was against the run of play and it hurt us," he told MarinersNet.
Slade: Too easy
"They came out to get the ball into the box where Stan would have been standing. I don't know about that rule. All I know is that it has hurt us twice this season.
"We haven't got a goal away from home. I thought that some of our play again deserved an half time lead but it didn't happen.
"Second half, effectively the second goal was a bit of a killer for us. It was all uphill from there.
"We need to look at the goals. It looked far too easy for me. The ball coming in at the back stick is just there to be put away.