SQL4304 installing jar file with sqlj for stored procedure

Using call SQLJ.INSTALL_JAR() on our system i to install a jar file 
works fine.

trying the same on the customer system i we got the following error:

call 
sqlj.install_jar('file:/qibm/userdata/os400/sqllib/function/jar/ggsprd/sp_bedarf
_auftrag.jar', 
'sp_auftrag_bedraf.jar', 0)

SQL State = 58004 SQL Code = -4304 SQL Message = [SQL4304]  Die gesp. 
Java-Proz. oder benutzerdef. Funktion SQLJ.sqlejReadJ mit dem spez. 
Namen SQLJ.sqlejReadJ konnte Java-Klasse com/ibm/db2/app/sqlejProcs 
wegen Ursachencode 1 nicht laden.

The German-Message means, that the function sqlj.sqlejReadj can not load 
the java-class com/ibm/db2/app/sqlejProcs with RC=1

Maybe a problem with the classpath

I can not see any difference between our system i and the customer machine.

any idea