Diagnosis
According to your Customizing settings, during input tax distributionfor line item &v2& with reference key &v1&, the system does notget the option rate from the account assignment object. Instead theoption rate comes from the assigned correction object. However, acorrection object was not yet assigned to the line item.
If the original account assignment object is an asset, then, regardlessof the Customizing settings, it is absolutely necessary to assign acorrection object for option rate determination.

System Response
The system cannot determine the option rate for the distribution.

Procedure
Assign a correction object to the line item.