iBooks author font substitution problem

Hi

Ive now been using IBA for a month or so and have to say its a frustrating piece of software.

This is my latest issue that i cannot resolve.

Ive been building a book for 2 weeks which is at the publishing stage and then all of a sudden when i opened it this morning it tells me that a font is missing and substitues it.

But the font is there and i can change everything back by appending the style sheets. Then if i save and close then reopen it tells me the font is missing again.

I do use Suitcase Fusion but have taken the step to put the fonts i use in IBA only in Font Book as .ttf's.

Also if i open the file on my Macbook, there is no font substitution and the book displays correctly even though the fonts in Fontbook are the same ones as on my iMac.

(Pulls hair out)!!!!

Anyone have any ideas??