DLookUp To Divide A Field In One Record By The Same Field In Another Record

I'm fairly new to setting up Access databases. Been learning a lot. Ran into a snag that I'm hoping you can help me with.

I am using a form to display text labels and running statistics for our jail.

The form, "Complete_Worksheet" gets its data from a query, "qryComplete_Worksheet". Fields that make these up are:

ID (key)
Standard (text)
Outcome Measure (text)
Numerator/Denominator (text)
CalcValue (number)

ID, Standard, Outcome Measure, and Numerator/Denominator are queried from a table, "tblComplete_Worksheet". CalcValue comes from another query, "qryDataSelect". My problem is this:

In the final calculated statistic, some records are numerators and some are denominators. I need one more field, which I have been trying to create as a calculated control on my form which will divide each numerator CalcValue value by the denominator CalcValue value following it. Since these values change constantly as new data is entered into another data table, the calculated control needs to also change with them. I have been attempting to do this using the following expression:

=DLookUp("[CalcValue]","Complete_Worksheet", "[ID]="&"[ID]-1"/[ID]=")

I keep getting a #Error message in the control in form view. When I run the expression in the Immediate window, I get a Compile Error:

Expected: line number or label or statement or end of statement

Any suggestions on how to make this work?