Can you use Sumif for a CalculatedControl in an Access Report -

I have a report that has groups. Above the groups, in the report header, I want to show a summary of the total Debits, and total Credits, broken down per industry, Internet, Cable etc.

The report currently shows

RCS
--Supervisor
----Employee
------Debit, Credit, Type.

if I put a control at the top of the report, and say =sum(Credit) it will give me a sum of credit for everything, I need it to break down by Type.

Debit -- Credit -- Type
$50 -- $100 -- Internet
$30 -- $50 -- Cable

Will SumIf work on a report? I don't see if in the access help section, but it seems like it would do the trick.

EDIT1:

Just found the Dsum again.
Tried this, but it keeps asking me for a value for the report?

=DSum([Credit],[Report].[rptCS3Detail],"adjReasonCode='DNU'")

rptCS3Detail, is the report, where the textbox is

Edit2:

Tried a few other ways, but get #Error

=DSum("Credit","rptCS3Detail.RecordSource","rptCS3Detail.Filter")
Was hoping, this would use the report data, and the report filter.
Also tried
=DSum("Credit","qryCS3Detail","rptCS3Detail.Filter")


Edit3:

Well, I found "a" way to do it. But it's not very dynamic, and it's a very patchy/bugy kind of way.

I created a textbox on the form that you pick data from.
I save the Where clause that I send to the report, in that textbox.
I also have to type in, each Item in the tblAdjReasonCode
=DSum("Credit","qryCS3Detail",Forms!frmKCreditDebit!txtGStrWhere & " adjReasonCode='Courtesy Credit - Internet'")

So I guess, now my question is, how can I do this better, easier, dynamic, and cookie cutter?