SQLi Question (SQLmap)

Hi guys,
I’ve got a technical question.. I’ve recently been giving SQLmap ago, just testing it out and seeing whats what but I’m having trouble understanding why it won’t work with the SQLi2 challenge.

I’ve already managed to get passed the SQLi challenges using the ‘proper codes’ (as i don’t want to give any spoilers away.) My question, is howcome SQLmap doesn’t find the GET parameter injectable?

I’m probably being very dumb but if anyone can shed some light on this i’d be grateful!