Need help on Summary display value for a series

Hi,

We are having this issue while displaying the summary value for a series when more than one level is selected by user in the worksheet.

We have a series C () for which we are using the client expression which is to calculate the ratio of Series A and Series B.

Client expression used is:

if (  getrow ( )  < forecastfirstrow()  , if(  Series B = 0 and shipment history > 0 , 1, ((  Series A  -   Series B ) /  Series B )), if(   Series B = 0 and  Series A > 0   ,1, ((   Series A  -   Series B ) /  Series B )))

There is no server expression we are using here.

Attached are the details with example and series configuration screenshot. Any help on this is highly appreciated.