There's pity in her look. Indeed, she pities him enough that she's able to resist the urge to say something irritable in response to being snapped at. Instead, she smooths down the paper, looks critically at the text on the page (dreadful handwriting, Bartimaeus has) to make sure she's got it all right, and then tries again.

Again, nothing.

She lowers the page and says to him, gently, "It's not going to work. The rules are different here."