I came across a few sentences....
- He 'slipped up on' just one detail.
- Someone had 'slipped up on' the order.
I do understand what slip up means - to make a mistake. But what about slipping up on something? Does it mean, for example in the second sentence, that someone made a mistake while taking an order? Like, they wrote down a wrong address perhaps? I can't seem to understand it, since English ain't my mother tongue :/ Please help me understand it.