Previous task assignee

I have a process application in oracle process automation and in the first task of a swimlane i choose as task assignee through user expression, a user that i have stored on a process variable. What i want is the next tasks of that swimlane to be assigned to the same user, so i choose "Assign to previous task approver in current lane". The result is that the next tasks are assigned to the swimlane role and not in the user of the first task. Any ideas on how to resolve this?