Report Designer and the LOOKUP function

SOLVED
I have work in process report with the "JC-Transaction Record" as the primary record.  We are beginning to set up our jobs with the account prefix entered at the job category level.  I've figured out how to condition the report to include the costs by account prefix. 
 
However, we enter our contract schedule of values in the contract module and that is where the account prefix is entered for each SV item.  My issue is that the account prefix doesn't come over to job cost with the schedule of value data after it is entered.  So I need a way to access the account prefix in the CN module. 
 
To do this I wonder if I need to create an ASUM formula for the contract item amounts for my jobs based  on the account prefix field.  This field is located within the "CN - Contract Item Record" field list.  I believe this will require using a LOOKUP function formula (and maybe even a custom sort order) but I have been unable to properly write it. 
 
If anyone has any guidance on this I would appreciate it.