database level is: DB2 v9.1.300.257
operating system is windows 2003(32bit)

Account er1adm is instance owner, but when issued the following command, got SQL0440N error. Please advise.

C:\Documents and Settings\er1adm>db2 values( RTRIM( CURRENT SERVER ) )
SQL0440N No authorized routine named "RTRIM" of type "FUNCTION" having
compatible arguments was found. SQLSTATE=42884

just as the message said, there is no such function RTRIM() that takes a datatype same as CURRENT SERVER .

you need check sql ref to see whether there is a RTRIM built-in function(I assume you are looking for the BIF one), and what's the argument type it expects

His statement runs fine on my DB2 for Windows system with 8.1 FP15.

put that statement in double quotes and remove all the spaces in side the braces