Count per line item on SAP Crystal Report

I have a set of data in Crystal reports that looks like below: You can see that each item, they have corresponding quantity.

However, there are no suppressed details in the report then the line-number should be equal to RecordNumber. So the following formula I got is:

WhilePrintingRecords;
NumberVar ItemNumber;


ToText(ItemNumber, 0) & "/" & ToText(Count({rpt_PackingSlip.LineNo}, {rpt_PackingSlip.WorkOrderNo}),0)

which resulted to:

Notice that it sums all the records in 1 SalesOrder.

But my desired output is:

Abbey should be 1/1

Charlotte should be 1/1