iCal not accepting password

I try to activate my filemaker calendars on iCal, and get this error.
The server did not recognize your user name or password for account “[email protected].” Make sure you enter them correctly.
I KNOW i entered it correctly. I am wondering if there is somewhere I should start looking first?
The server did not recognize your user name or password for account “[email protected].” Make sure you enter them correctly.
I KNOW i entered it correctly. I am wondering if there is somewhere I should start looking first?