Probably cause you don't have Choza

You don't have enough stars to unlock it. It shows that in your screen shot.

Yea,but hes right there,should his stars count?So confusing.

you need that many stars to unlock it, ninjas already unlocked from the treasure do not count.

Hi! On the left, you can see the amount of stars you have over the number of total stars (This is based on the ninjas you have unlocked in the Collection Scroll that are active). The reason why Inoichi does not count even though you have him recruited is because his column is not unlocked yet. His column requires another 6 stars to unlock, which means until it is unlocked, his stars do not count towards your total amount of stars. Once the column gets unlocked, any ninjas you have already recruited that are in their respective column will count towards the total number of stars you have (shown on the left). Hope this helps clear some of the confusion =]