I've been trying out Naruto Shippuden: Ultimate Ninja Storm Revolution recently, and it doesn't seem to make any sense when you can and can't use your ultimate or team ultimate jutsu.

When playing as the ultimate jutsu type, there's a reddish-orange bar to the side of your health that seems like it would indicate this. However, I have on occasion been able to use ultimate jutsu when it's not full, and I have also on occasion not been able to use it when it is full. So that bar seemingly has no bearing on ultimate jutsu, unless I'm not understanding it.

There's also some cases where there's a popup showing the button combination to press to use the ultimate jutsu, but I've been able to use it without that popup being present.

What are the exact circumstances under which you an use ultimate jutsu? How can I tell mid-battle?