I'm with madbuyer, sounds like it's locked up (pun not intended). If lubing it through the key hole doesn't work for ya the next thing may be to remove it from the triple and play with it to get it working.
Have you tried working the bars slightly when at full lock? Sometimes mine gets a little finicky. Also try and see if anything is under there obstructing the pin.
The key works just fine otherwise correct?
2001 #62. Ohlins rear/valves, Micron high mount, HyperPro damper, SharkSkinz, Tyga billet triple clamp, Tyga Carbon Fiber fender and hugger, Ti bolt/custom subframe/alien motion 8 cell diet, 15/41 520, COP conv. PCIII, Venhill lines, modified air box, turn signals in headlights...<deep breath> ZG Touring windscreen, Tech G rear sets, CRF450 rear master w/HRC cover, Tokico 6 pots w/V-pads, CRG Bar end mirrors, PSR Shorty levers-use only clutch, wanna-be basic racer paint, Roman Gold PC wheels