Had quite the same problem loading data from SAP ECC.
In SAP ECC the hierarchies are stored in the tables SETNODE and SETLEAF. According to the hierarchy there are also intervals in the SETLEAF table.
Once I had loaded the node values (in your case as ex. B6 as part of the transaction data) as well as the hierarchy intervals (ex. B5 - B15 as part of the hierarchy data) into qlikview, you have to do a IntervalMatch to match the values to the intervals.
In my case I had the account number RACCT in the transaction data table and i linked it to the intervals in table SETLEAF as follows:
inner join IntervalMatch (RACCT) Load [VALFROM], [VALTO] resident SETLEAF;
hope this helps a little further, although it's not exactly your SAP BW case.