Preconditions with two status's

Hi All

I'm trying to create a condition where the change looks at the status of the child tasks.  if there are two tasks - one with completed and one with RFC accepted, I want the precondition to return true.  I have this, but get the dreaded XML(1,1) error:

import System

static def GetAttributeValue(Change):

Value = 'False'

if Change.Tasks.Status.Title == 'RFC Accepted' or Change.Tasks.Status.Title == 'Completed' : Value = 'True'

return Value

what am I doing wrong. ( I have a feeling I need a for loop but would like some guidance)

ta