Diagnosis
You have changed the definition of fields of the table in the ABAP/4Dictionary. However, a physical table containing data has already beencreated in the database for this table. To ensure system consistency,you must adjust the definition of the database table to correspond tothe logical table definition in the ABAP/4 Dictionary.

Procedure
Convert the table using the database utility (SE14). To do this, selectthe Convert function in the utility for database tables. Thedata in the table is kept when you convert the table.