Picture Turn back to Previous

Situation: After i changed Picture’s source by ‘this.diagram.model.setDataProperty(obj,‘src’,p.src)’,
this view of picture changed. But when I tried to pull a line from the Picture with no link, the Picture source just turn back to the previous…
Someone know why?

Did you execute the call to Model.setDataProperty within a transaction, so that when the user starts a transaction but then cancels it, causing it to roll it back (rather than committing the transaction), the rollback will not undo your call to Model.setDataProperty?