Error while creating a purchase return order

Hi everyone,

While trying to create a purchase return order using Get Posted Document Lines to Reverse, I got the following error message:

One or more return document lines were not inserted or they contain only the remaining quantity of the original document line.
This is because quantities on the posted document line are already fully or partially applied.
If you want to reverse the full quantity, you must select Return Original Quantity before getting the posted document lines.

What can possibly be the cause of that??