can't find font

I want to use ITC Avant Garde Gothic Book in Indesign. It's showing in Font Book and it's used in an Illustrator file but isn't recognised in Indesign. I'm trying to open an ID file which has the font in it but get a Missing Fonts message with a Find Font button. Clicking the buttons opens a font search option but it's not showing in the font list. Does anyone have any ideas please on why this is happening?

thanks