I think it means you are missing a key piece of equipment and therefore you can't play.
Go to 'my profile'. Click on it.
Click on 'equipment' and then 'edit equipment'
Look along the top row where it shows what clubs you have in your bag. Does it show that you are missing required clubs? The irons? The putter? The ball? If you are missing them, then you need to re-equip them.