You've got a few different questions here and I'm not sure I understand everything, but I'll do my best. First, yes, as a table gets bigger, DLOOKUP on that table will slow down. That's inevitable. What you could do is make the set of records in it smaller with filters. For example, if you're working with products, add a product category combo box, and filter the products based on that using cascading combo boxes. Filter out unused products. Filter alphabetically. There are a million things you could do to shorten that list.

You should be able to perform functions like SUM in form headers, footers, and in subforms. But again without knowing exactly what you're trying to do, it's hard for me to say for certain. If you are trying to access a value stored on a subform FROM the parent form, it would be Subform.Form!FieldName.

WOW after trying and trying I used the trouble shooting checklist... there is a method to the madness thank you Richard. I forgot that my subcost has an if condition.  regtime and non regtime.  if check mark is true then retime * qty, =false nonregtime * qty.  the result is stored in subcost.  I am converting it to a Val getting the end result.
I put the =val(subcost]) which has the if condition on the subform and I get the right number.  And it works, so I ref the text box in the footer of the subform it gives me the right number.

Sorry Alex I called it txet48

So I called text 48 on the main form on the footer section  ERROR
Subcost = Val(IIf([isregtime]=True,[regtime]*[qty],[nonregtime]*[qty]))
Text48 = ([subcost])   this returns the correct number for cost
=[EstimateTsubform].[Form]![text48]  this returns an error
Where did I go wrong?
I even used the expression builder tool thinking this will fix it... ahhhhhhhh need more coffiee

V/r
Juan

All I see is a jumble of field names. Without knowing WHAT everything does, it's very hard to tell. Your names all LOOK fine, but make sure it's all spelled right and points to the right stuff. Without looking at the database in action its very hard to troubleshoot. Maybe MsgBox stuff each step of the way and see if the values come back right? Alex is right. Text48 makes it impossible to know what that is. Can you MsgBox it from a button in the same place as the field that's trying to read its value?

Richard THANK YOU the msg box showed my eror got it to work now I can put this tto rest and do the check list .... Thank you for you

v/r
Juan

Glad to help. Remember: spelling is important, and MsgBox is your friend. :)