Hey :)
You have the three default zones. You need to add a specific one for your IP address range. Right click on Reverse Lookup Zones and create a new Primary (AD Integrated if applicable) zone. Name it "192.168.1.x" or 1.168.192.in-addr.arpa (the two being equivalent and dependant on the box you use).
Enable Dynamic Updates for the zone, then on your server run "ipconfig /registerdns" you should find a PTR record appears for your server.
Running NsLookup after this should be error free.
Chris