Location change Query in SRM

Hi,

Have a question on Location change in SRM- Extended classic scenario.

When system allows changing the location in SRM.. My observations so far..

PO transferred to ECC- No subsequent document- Allowed

PO transferred to ECC- Subsequent document generated- Now allowed

PO transferred to ECC- Only Down payment created/reversed - Not allowing-  With error- Back End Error:Plant can no longer be changed

Ideally if the subsequent document revered it should allow right ?

BR

Srrimaan