</pre>
You probably haven't set the pools up properly.
Please read the most recent thread on "ns_db not enabled" problems. Someone posted their entire nsd.tcl file there, and there was more discussion about these problems.
Also, you should include the full ad.ini (or even better, source the ad.tcl version in your nsd.tcl, because you only have to change your server name, etc once at the top of the file). There are places that will break with bad queries if they can't find the parameter they're looking for. Won't cause the error you're seeing, but will cause further problems down the line.
