Message Center Annoyance!!

anybody with this issue? I have a 2000 windstar and the message center keeps showing "Oil Change Required" even after an oil change. I can clear it by pressing the reset button and everything works fine but the "oil change required" comes back when engine is started up again...I tried resetting, recalibrating ect... and that did not work, I'm sure there is a simple fix for this...Any suggestion would be greatly appreciated.

Thanks