Addon does not correctly calculate pet talent points and as a result the addon must be disabled before speccing the pet. Addon shows many more talent points available to pet than actually are and does not allow assigning available talent points.

Noticed the same issue as I was just going to start level my hunter.
Says I have available points when I don't, plus can't interact with the frame even when I do have available points.

This issue has unfortunately been in since the release of wrath and without a pull request it's unlikely to be fixed, since the author doesn't have the time to fix it.

It's actually a lot worse than 'wrong point count'.

Right now my pet doesn't have Grace of the Mantis. Instead it has Great Resistance; it doesn't. It actually has 2/2 Grace of the Mantis.

If you want to spend the points correctly. You'll need to disable the mod, spend them, re-enable it.