No log, eh?
You will have a log of problem debugging then....

There are several reason why it might be like this.
First of all, does this statistic exist in statserver?
The fastest way to check would be to see if you can get the same value using CCP.
Can you see the value in CCP? (Since you can create an identical request in there for the same DN)
... wait a second....
I am curious - how can you get a DN-related status from Agent?
From Person - yes, if you have DN assigned to it, but from agent...
Can this even be done?
Where in the manual did you find that this is supposed to retrieve something?