SAP Message BRF565 - BRF expression '&1' cannot be calculated

Diagnosis
Expression &v1& uses the CASE expression &v2&. An error occurred duringthe attempt to crate a data object of BRF type &v3&.

System Response
The system cannot create any data object.

Procedure
Call up transaction BRF.
Enter the application class &v4&.
Check the following with BRF expression &v2&:
Result type
Field/structure length
Decimal places