It is an open type font so should work, but it looks like the problem is that it hasn't installed correctly in Illustrator. I am using Windows 7 so right-clicked fonts and clicked install. Fonts appear in fonts area of control panel and install in disabled when font is viewed. they work correctly in other apps, such as Word
When I vew the VistaSans fonts (in existing file) in Illustrator, they appear in the fonts drop-down, but have an asterisk beside them (i.e. not installed) so how do I get them to install correctly in Illustrator? Font isn't appearing in Photoshop either.