OnChange Ajax Event no process on a date field

Hi, I have 2 date fields. I need that when the user changes the first date, it should add 1 day to the other date. I have tried to do this on the ONChange Event for the first field. But nothing happened. I tried to display a javascript message in the ONChange, but the message is not displayed either. Does any body know if the Date field process the OnChange ajax event? or can you give me an idea on how to change the second date when the first date is changed?

Thanks in advance