Alma 46:6

Thus they were led away by Amalickiah, to dissentions, notwithstanding the preaching of Helaman and his brethren; yea, notwithstanding their exceeding great care over the church, for they were High Priests over the church.

Amalickiah led them away to fight against each other. This happened even though Helaman and his brothers were preaching. Helaman and his brothers took great care of the church because they were high priests.

So despite everything Helaman and the other high priests were doing to lead the church well, Amalickiah was pulling people away into rebellion.