Holidays not working?

Holidays not working?

Hi,

I've configured some holidays in my portal. They do show in the portal that i've created them and if i look at the gantt view it highlights those days and indicates they are holidays. The issue i'm having is there are tasks currently scheduled for those dates. When i added the holidays, it didn't move those tasks. they are still scheduled on those dates.

How can i make tasks to ignore holidays?
Thanks
Rob