since they had been unable to keep it at the regular time, because not enough priests had consecrated themselves and the people had not been gathered in Jerusalem.
KJV
For they could not keep it at that time, because the priests had not sanctified themselves sufficiently, neither had the people gathered themselves together to Jerusalem.
ASV
For they could not keep it at that time, because the priests had not sanctified themselves in sufficient number, neither had the people gathered themselves together to Jerusalem.