Calculating null fields in a form

[chu3w]

I have a main form and a subform. Both of the forms are pulling information from the same query. The query has a month and a revenue field. The main form pull revenue for the month of January and the subform is filtered to pull revenue for february. On the main form I have a text field that will add revenue for both months together. My Problem is if there is no value for February then it will not add the revenue together. I tried using the nz function that looks like this



=nz([Forms]![MainForm]![Revenue],0) + nz([Forms]![MainForm]![Subform]![Revenue], 0)

This doesn't work

[pbaldy]

I use this:

http://www.mvps.org/access/forms/frm0022.htm