Take a look at the attached. Look at Form1. You can see your two fields plus one that I've added that shows the number of days difference. If you go into edit mode for the form then look at the properties for that field you will see where I've entered the datediff funtion.Note that this field does not get stored anywhere. It is "unbound".
Another way of doing what you want is this: I've created a query (query1). If you examine it in edit mode you can see how I've added a field for the datediff function. I have then created another form (Form2) that uses this query as the source date and the NoOfDays field in the form is based on the calculated field in the query.
Picked up the DB yestreday with the intention of replying today, glad I looked in before doing any work, I don't think I could have done more than Stopher.
BTW Icemac by stripped down I meant just a little data, and maybe, if necessary, remove reports etc not pertinent to this problem.
Hope you are ok with Stopher's examples.
Brian
PS Don't worry about being a noob we all were once.
O im not worried im learning alot from the forums. The little example helped loads and i know now what i was doing wrong. Thanks everyone for helping me with problem.