Qp0lProcessSubtree.... sigh

Hi,
 
I've written an RPGLE pgm to retrieve the owner and created date
attributes of IFS objects, specifically of type *LIB, *FLR and *DIR.
 
The pgm structure is simple: 
1. the main pgm calls the API Qp0lProcessSubtree - the API parms include
where to begin the parsing (for which I specify root "\") and what types
of objects to look for (I specify *LIB, *FLR and *DIR).
2. the API takes care of the recursion of parsing the IFS tree, and
calls a user exit program for each matching object it comes up with.
3. the user exit pgm (also written by me) calls another API, Qp0lGetAttr
to retrieve the required attributes.
 
Now I was testing this and I'm facing a weird problem at the very first
step. 
 
When I give the starting point as \QDLS and type as *FLR, this program
works fine. But when I give \QSYS.LIB and *LIB, I get error EINVAL
(invalid parameters) on Qp0lProcessSubtree. I checked the manuals and
this API should work for the QSYS.LIB FS. But still, I can't get it to
work. 
 
Please help. 
 
Thanks.
 
______________
Shantanu Biswas
(469) 220-5933