POI, HSSFR4 and Debug

Hi, I wrote a simple program to read an Excel file, modify some cells and
write back on the Ifs. Of course, since I'm an rpg programmer, I used the
service program provided by Scott Klement (HSSFR4).

The problem is when I run the pgm from the command line I've got an error 

Message . . . . :   Java exception received when calling Java method.
Cause . . . . . :   RPG procedure HSSF_OPEN in program xlib/HSSFR4 received
Java exception "java.io.IOException:" when calling method 
"<init>" with signature "(Ljava.io.InputStream;)V" in class
"org.apache.poi.poifs.filesystem.POIFSFileSystem".

If I call the same program using the debug (STRDBG PGM(LE36) UPDPROD(*YES)
SRVPGM(HSSFR4)) it's working perfectly.

POI .jar files are in /QIBM/UserData/Java400/ext.

Any hint, idea or...

Thanks in advance

Marco

P.S. I saw the thread in:
http://archive.midrange.com/java400-l/200505/msg00133.html
but he ended up writing Java code to fix the problem.

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