date problem

hello i am running into some trouble with a very basic problem. i want to insert the current date/time into my db. i have the field set up as a datetime field. when i submit info, i just get a blank date, i mean it all zeros, like 0000-00-00 00.00:00:00. how do i insert the current datetime into my db? i tried using a hidden field with a foramtted gmt date value, but its not working... any help thanks - eoghan