VS 2005 Express Database - Two Linked Tables

One of the things I'm trying to do is work out the total profits for a company, reading from an access database comprising of two linked tables. All the information needed for the calculation in question (Fees, Sold/Bought?, Cost/Income) are found in one form (Financial) and I want to read this information and carry out the required calculations within a sub.

Here is the calculation in Pseudocode I wish to do:
Do
If SoldBought = Sold then
Total = Total + Cost/Income - Fees
Else: Total = Total - Cost/Income
Read Next Record
Loop Until End of Records
[Code] .....

Unfortunately, I encounter an error with the above. I get the following error;
"There is no Row at position 0".
How I could get this in motion - I've been stuck in a rut for days trying different things out and I've come to accept that I can't do this alone.