[SOLVED] Problem with planned end date

Hello,

I have planned a project which should have started last year in August. The validated start date was 22/08/2016 and the end date 30/09/2016. But now we could only start at 13/06/2017. So I set the project on ‘in progress’ on 13/06/2017 but didn’t change the validated dates. The program changed the planned date to the actual start date but didn’t change the planned end date. So I got an error note because the planned end date is before the start date. But now I can’t change anything. Is this a bug or is it my mistake? What can I do?
Enclosed I send you a screenshot of the problem. As you can see the gantt chart is right.

Thanks you very much for your help!

I did it already. So the bar in the gantt chart has 'slipped' to the correct date. But the written planned end date in the activity didn't change.
And I also cann't change the validated end date to the future now. (see file attached)

Yes, we use already V6.2.5
Do you need any more niformation?