The Sky Blues had to settle for a point after a goalless draw against Chesterfield at the Proact...
The home side were reduced to ten men with over 20 minutes left in the contest, and Willis believes it is a disappointing result given the circumstances.
"It's quite disappointing coming away with a draw, especially when they've gone down to ten men. We've struggled to break them down, but a point away from home is something to build on on the back of two losses," Willis said.
"Marc is scoring in training, I think it's just a case of getting one and then they will continue to come, for him and the team.
"It's good to have somebody like Jodi Jones on our team. He was a constant threat today and at only 19 he is still very young. Once he starts to know the game a little better he can be almost unplayable at times."
With the recent struggles being in front of goal, the Sky Blues have the joint-best defensive record in League Two, conceding just three times in the opening five games.
Deadline day signing Tom Davies partnered Willis at the back today, and the 23-year old is looking to form a good partnership with the latest addition.
"A clean sheet away from home, you'll take that anywhere you go. We were unlucky not to score today but with a couple of home games coming up hopefully we can get the goals there.
"Defensively everyone has got a job to do and everyone is doing that. We aren't conceding many goals and hopefully when we can get one more goals will follow,"
He added: "It was good playing alongside Tom. We had a training session yesterday where we got to play together a little bit. If he continues in the team in the next game hopefully we can build a good partnership."