Error when sorting with german charakters

As a Newbie I tried to solve the problem of sorting the result of a query in
the following way:
-------------
SELECT ........... ORDER BY
REPLACE(REPLACE(REPLACE(REPLACE(UPPER(NACHNAME),'Ö','OE'),'Ü','UE'),'Ä','AE'
),'ß','SS')";

The following error occured:
SQL error: [SAP AG][LIBSQLOD SO][SAP DB]General error;-1013 POS(1281) Too
many order columns., SQL state S1000 in -SQLExecDirect
--------------
When i use:

SELECT ........... ORDER BY
REPLACE(REPLACE(REPLACE(REPLACE(UPPER(NACHNAME),'Ö','O'),'Ü','U'),'Ä','A'),'
ß','SS')";

...it works fine
--------------

My question:
Is this a limitation of the ODBC-Driver
or could this be solved by changing any configuration entry?

May be there's a better way of sorting?

With kind regards
Horst