@aamra, here’s an attempt at your custom report. First a Customer Statement (Transactions) from a modified Northwind file for the customer Alfreds Futterkiste:
It is not possible to reproduce the running total, but the following custom report, as a supplementary statement, may be helpful:
The edit screen:
Because it does not show completely in the above, the Alias for the TransactionName is: Date<br>     Description - Reference - Date
Notes on the Where section:
For the custom report, data is needed from these accounts:
Cash at bank
Cash on hand
GST payable
Inventory - sales
The Where filter does not have “or” logic to get data only from the above accounts. So, “does not contain” is used to exclude other accounts and their unwanted data. Only you know your Chart of Accounts so if necessary exclude additional accounts by adding additional “does not contain” lines.
In the Where filter the line “Contact” is used to generate a report for a single customer. I’ve seen elsewhere that you have tried “Customer code”. That should work in place of Contact.
If you have multiple sales invoices to the same customer on the same day you may want to add another line to the “Group by” section:
