Why do all my allies say cannot call this unit

Im very new to the game and when i quest or battle i cannot call any allies into battle why is this ?

It has to do with when they are online and how close in level they are to you. I believe they will be active for an hour if they are online and they are around your level. I also know that if they aren't close to your level, you might only be able to use them for 15 minutes or so. It's kind of a bummer.

Never heard of the level thing, although I have noticed occasionally an ally can be used for 2 hours instead of one (typically a low-leveled one... I don't have anyone much higher than me).

By the way, people always seem confused by this, but at the very beginning of the game it mentions that because you're new, you can use allies unrestricted for a week. Once that week is up you can only use allies that have been online recently (typically within an hour).

You are correct. It is worth your while to boot inactive allies.

Also, when you search for new allies, they are listed by order of when they last logged in, so make sure you add your allies during your normal play time.