'Unable' in the Bible

and the priests were unable to complete their duties because of the cloud, since the glory of the LORD had filled God's Temple.

Useless troublemakers soon gathered around him, who turned out to be too strong for Rehoboam, because he was young, timid, and unable to withstand them.

As a result, the Lord became angry with Amaziah and sent a prophet to him, who asked him, "Why did you seek the gods of a people who were unable to deliver their own nation from you?"

Because there weren't enough priests, they were unable to prepare all the burnt offerings until other priests came forward after having consecrated themselves, so their descendant of Levi relatives assisted them until the services were complete. (The descendants of Levi had been more conscientious in consecrating themselves than had been the priests.)

but they had been unable to celebrate it then because not enough priests had consecrated themselves and the people had not yet been gathered together in Jerusalem.