task user name incorrect

Hello,

we are assigned tasks to the users (throw user name or active directory group).

and we using k2 API in order to take action.

when assigning a task to a user by user name (Task user:name) correct but when assigning the task to the group  (Task user:name) wrong.

(task user:name ) always equal the destination, not the person who tasks the action.

we take the action from workspace everything is ok.