Paul Ince's men found themselves two goals down at the break and although Jermaine Easter's brace dragged them level, Robinson has urged them not to keep on making the same mistakes.
He said: "Being brutally honest, the way that we committed ourselves in the first half wasn't good enough and we can't keep making the same silly mistakes.
"The players need to stand up to be counted and we told the players a few home truths at half-time being two down and they came out a different team in the second half. Individual errors are starting to cost us and we won't accept it.
"We've been on a disastrous run conceding goals recently and we can't let that continue. It's very frustrating to give good sides like Millwall a two-goal lead."