I'm with Beanache, sounds like a battery problem. Yank the battery and take it to your local autoparts or battery store to check the volts under load, only takes a few minutes and is usually free (at Autozone, etc.)
Make sure the positive/negative leads are installed correctly. My Battery Tender charger won't work if installed incorrectly, but not sure about your Datamate.
My '02 battery is still going strong, but it's had a winter maintenance charger since new. (hope that didn't curse me!)
If the battery checks out, might want to replace the starter relay under the tank. They're only $11 and mine went bad last year. My bike wouldn't start about 50% of the time, no turn over or clicking, just dead. The tech at my local dealership said it was the starter solenoid, they ordered a relay by mistake. I went home put the relay in and the problem has never returned. (they never did call to tell me my solenoid was in!)
