custom spell books

for my map(see sig.), i am making 7 different custom spell books with 3 spells each. I based the items off of the original spell book and based the abilities off of the original spell book ability. My problem is that some of the spell books cost a certain amount of mana to open while some do not.

That means you don't have enough mana to cast any of the spells in the book, it doesn't cost mana to open the book.