Hi Tejo,
Your database must be created with a collation in which accented and unaccented versions of the same character to be considered different.
There are options to do this in the create database statement and the dbinit utility. You will most likewant to use a UCA collation for your database.
http://dcx.sap.com/index.html#sa160/en/dbreference/create-database-statement.html
hth,
--Jason