Right. This is so so so simple i cant believe it. Steps:
1. Go to your layers tab.
2. scroll up.
3. unlock ALL the layers you can
It will work; trust me, I had the same prob, (faded the lock on mine to) and this worked swell!!!
Another helpful tip... if you click the alt/option key on the lock toggle it will lock or unlock all your layers. Note though,,, sometimes your sublayers will still remain locked. Usually repeating the Alt click + lock toggle will release the sublayers as well.
*Note all things locked in the master page layer(s) have to be unlocked and edited when you are in the master page.