3000 is well not refrence a topic name but rather it refrences the 3000th topic, which i assume there isnt one. This is the reason for the $null return, correct as per the help file.

The problem is that it is impossible to count the number of entries in a topic which has a numeric name, and I consider that to be a significant bug since there does not appear to be any workaround.

* Quietust, QMT Productions
P.S. If you don't get this note, let me know and I'll write you another