Upgrade issue for {{each}}

I am upgrading my application to ember 1.9.1 from 1.8.1. I got a deprecation notice for {{each}}

DEPRECATION: Using the context switching form of {{each}} is deprecated. Please use the keyword form ({{#each foo in bar}}) instead. See http://ift.tt/1BOOESD for more details.

I have this each statement where bands is an array of objects

{{each bands itemView='matrix_band' itemController='matrix_band'}}

I have tried several options like

{{each band in bands itemView='matrix_band' itemController='matrix_band'}}

but the band object is not being passed to my controller correctly so I can not access any values off of the band object.