Date calculation

I want to calculate "Start Date" field by using "Date Required" field and a record that contains leadtime values eg. 5 days.
The result should be that if entered required Date is on 2/9/03 and there is 5 days leadtime the calculated start date should be 28/8/03.
I got as far as working out that I'm using the DateDiff function in the Expression builder. But I'm not clear how I can use this.
Any help is much appreciated

Hi there
Assuming your Date Required field is a textbox, likewise for Start Date, then perhaps u can try these codes:

Private Sub txtDateRequired_AfterUpdate()

Me.txtStartDate.Value=Me.txtDateRequired - 5

End Sub

U will need to format the textboxes to date (for e.g. Medium Date).

Cheers...