Can't modify to Aulani or VGC?

[Hoops McCann]

Sorry if this is a newb question, but today while trying to modify a reservation I noticed that I can't select Aulani or VGC. Those check boxes are grayed out.
I don't want to go there anyway (not for this trip) but was surprised, and feel like I hadn't noticed that before on the modify screen.
If I attempt to make a new reservation for those same dates and resorts I can.
Why is this so?

 

[davidhr]

It’s to block people from accidentally modifying a reservation to the west coast/Hawaii.

 

[eticketplease]

Yes as @davidhr mentioned it is intentional.

AUL can only modify room and dates.
VDH & VGC can only modify between those two resorts, rooms and dates.
WDW, HHI & VB can modify between these resorts, rooms and dates.