SQL function problem

A couple of months ago I got my feet wet with SQL and a number of you
helped.  One of the things given to me was an SQL function called ISOTODEC
which converts an ISO date field to decimal YYYYMMDD.

At month end there is a file reorg that failed at the end of June that
utilizes ISOTODEC in an SQL stream.  When I came into the office and ran it,
it went fine.  I never could find the problem though.  The error said
"SQL0204 Position 1 ISOTODEC in *LIBL type *N not found"  I decided to wait
until the end of July and see what would happen.  Same result.  If I run it,
it's OK, if QSYSOPR runs it it fails with that message.

The only thing I can come up with is that I have a different library for
current library than everyone else.  The library that function is in is
DILGARD.  DILGARD _is_ the current library for all users on the system
except me.  DILGARD also appears in QUSRLIBL.  The function exists in the
users library list, and *PUBLIC has *CHANGE authority to it.

I'm kind of at a loss to explain why it says not found.  Any ideas?

Thanks.