Statistical log - No records returned

Question

We have a custom ABAP that calls function module SAPWL_STATREC_DIRECT_READ to extract data from the statistical log.  (We use this information to monitor the tcodes that a user has executed.)
A scheduled job runs the program runs each morning at 5AM, extracs data for the previous day, and creates a unix file.
The job always completes successfully, and on most days does extract the desired data.  Sometimes, however, no data is returned from the function module, and so a unix file is not created.  However, we know that there has been tcode activity in the system on those days.
<b>My Question</b>
From a Basis perspective, is there anything we should be looking at that could be responsible for what we're seeing, possibly some system parameters?  (Our Basis group has not come up with anything so far.)
<b> System Info</b>
We're at release 4.7  (Basis release 6.2)
Thanks in advance for any suggestions.
Len Laurence,
Becton Dickinson

Answer 1

Hi Tim, and thanks for taking the time to respond.
Over the past few days, I've been corresponding with Andreas Vogel, who has a blog on this site.  He's the SAP developer responsible for statistical monitoring and workload analysis tools such as ST03N and STAD.
He confirms what you're saying - that SAPWL_STATREC_DIRECT_READ reads statistics only for the instance it is run on, and has suggested instead SAPWL_GET_STATRECS_FRAME.  Have you had any experience with this function module?
I've updated the ABAP program (in our dev. system) to use the new function module, but it's difficult for us to "prove" that this is the problem, as it's only in our prod. system that we have multiple application servers.  To get something moved to production around here is an arduous process, with all the documentation required, so we don't want to go through the trouble unless we know that this will fix the problem. 
Hopefully, our Basis group will come up with a way for us to test this in the lower systems, and it will fix the problem.
Thanks again,
Len