Some contacts doesn't appear in their folder on the address book

[Ricardo]

Hello!
My question is why there are some contacts in my address book not listed?
I have a public contact subfolder (ex: Customers) and the option "Show this
folder as an address book..." selected. In the dialog box "Address book" when
i select this contact subfolder (Customers) it does not l. With other contact
subfolders i get the same problem, or even worst, when it doesn't list any
of them. I couldn´t see a solution... Any help would be great!
Thanks, Ricardo!