Help with nested function

Hi,

I'm trying to write a report that will return the sum of all the purchase lines for a particular contract/costcode in USD which is not the LCY, and frequently not the order currency either. To do something similar for another report, I've been finding the latest applicable exhange rate in the currency exchange rate table. This seems to work great, but I'm having trouble nesting it inside them the sum function for this particular report. I find it very hard to debug whether I've just got the numbers of quotes wrong, or if I'm trying to nest more than I'm allowed or anything else that I could be doing wrong. If anyone can assisst I'd be most grateful.

=NL("Sum","Purchase Line","=NF(,""Unit Cost (LCY)"")*NF(,""Order Quantity"")*NL(""Last"",""Currency Exchange Rate"",""Exchange Rate Amount"",""Starting Date"",NF(,""Order Date""),""Currency Code"",""USD"",""Company="",Company)","Job No.",Job,"Shortcut Dimension 2 Code","@@"&$D10,"Line Amount","<>0","Document Type","Order","Company=",Company)

The named range Job contains the Job No., Company contains the Company and D10 contains the costcode.

Thanks!

Teresa