Hi Nicole, a task can have multiple predecessors so you need to do a collection.
I have this text mode I've used in the past. It should the task number, name, and planned completion date of the predecessors for a task
displayname=Predecessors
listdelimiter=<br>
listmethod=nested(predecessors).lists
textmode=true
type=iterate
valueexpression=CONCAT("(",{predecessors}.{taskNumber},") ",{predecessors}.{name}," - ",{predecessors}.{plannedCompletionDate})
valueformat=HTML
Hope that helps.