Have recently done an oil change on my 06 ZZR600, and when starting up the bike to check for leaks...the oil light stays on. I have checked the oil plug and oil cap, and both are sealed and torqued to specs. The oil level is visualed at the top of the sight glass, it sounds, when the bike is slightly revved, that there is NO OIL circulating. I have done 3 other oil changes since my purchase and no problems until now. Question - Not sure what to look for next? Is the oil pump electric or mechanical? Any other checks I should do? Thank You.