Barnsley were unable to recover from conceding a fourth-minute goal to Amari Bell despite having 70 per cent of the ball. It meant they suffered a first defeat under their new Austrian coach.
The Reds were without the injured Carlton Morris, and the Belgian strikers they signed this summer, Obbi Oulare and Aaron Iseka, are still not at the fitness levels Schopp demands.
Without them, the hosts lacked the cutting edge to turn their possession into goals.
"We know how long this Championship is and of course I will have all my options on the bench at some point," said Schopp.
"Carlton was a really big miss for us. We could have had better options to win the first ball.
"This is something we had to handle right now.
"Today there was a lot of good stuff. I guess the lads deserved a bit more."
The transfer window is open until August 31, and Barnsley are still looking to add.
"This is something we are analysing and discussing a lot internally," said Schopp, who as coach is not in charge of recruitment, but has an input. "Right now we are a bit short of our options and we have to be really focused on what position we can add a piece to to give us something different.
"We have to take care of the left side because Ben (Williams) did a really good job in the first two games but he hasn't played for a long time and with Jordan Williams too we don't have them every day in training s it's all about how we can solve the problem but I don't think it (the absence of the pair) was a big issue for us tonight."
What he did point the finger of blame at was the team's defending and their taking of chances.
"I guess we were defensively poor," he said, "and we weren't as clinical as usual.
"We have to be much more clinical. That's definitely something we have to improve.
"We saw on Saturday how it is when you score and the opposition have to defend when you're 1-0 up (as Barnsley were at home to Coventry City).
"1-0 down at that stage of the game it's a tough one to find the right answers.
"We found good solutions, we created all the situations.
"The ball was in their box a lot in the second half.
"Defensively we were too poor. I'm not used to that because our defensive line is usually our most important tool ot defend.
"The good thing in this league is you don't have to think that much because you play again on Saturday.
"I think we are on the way. It's not that everything can change from one day to the next and we don't want to change everything. There are so many things we want to keep and just be better at certain details.
"That's the journey we're on so we have to be really focused.
"I guess in a couple of weeks we won't see these mistakes any more because they'll have more confident and able to play for 90 minutes."
On his forward options, Schopp said: "RIght now we are waiting for the last tests but probably (Morris) will be out a couple of weeks.
"This is definitely where we hope we get (Oulare and Iseka playing) as soon as possible. It's up to them to give us the right answers so we can put them in."