Dean Morgan netted two first-half penalties for Wycombe - the first in the third minute after being fouled by Scott Kerr and the second before the break following Jamal Fyfield's barge on Joel Grant.
Grant got on the scoresheet himself with a fine solo effort on the hour mark with defender Dave Winfield completing the 4-0 victory with a header 10 minutes from time.
"We're very disappointed from start to finish," said Mills It was a terrible start, we gave away two penalties. We're committing suicide at the moment," said Mills.
"We're giving away goals and we don't look like scoring and, at the end of the day, that's a recipe for disaster. We'll sort it out, that's our job. We'll get ready for the next one and move on.
"Football's about this. It's not all success, when things aren't going right you have to stand up and be counted.
"The players at this football club have got to stand up and start winning matches, start doing their jobs better. We know that, and we will.
"There's no hiding it. There's no excuses. We're giving goals away and not scoring goals. Jamal's told me he hasn't pulled the man, I've got the DVD so I'll see if he's telling the truth.
"It's a very disappointing weekend again for us again. Two weekends running and conceding four goals in both games. That's not good enough, we have to be better."