Cognos FM reporting

[cognos05]

Hi ,
I have mostly worked with dimension reporting in cognos and having one issue with relational reporting.

I wanted to show how much discounting vs promotions are given for a specific customer in a certain period .

My promotions and discounts are differentiated by the below conditions based on 2 fields in promo query subject .

promotions :  [AME Billings].[Promo].[Promo Code] <> '' AND  [AME Billings].[Promo].[Non Promo Exclusion Flag] = ''

Discounts  :[AME Billings].[Promo].[Promo Code] = '' OR  [AME Billings].[Promo].[Non Promo Exclusion Flag] = 'X' 

if the above case works then it has to subtract list price - sale price to get the values.

so i wanted to use a stacked chart in 11.1 which accepts only one measure so I created a calculated measure like

Measure : total(([AME Billings].[Billings].[Revenue At List Doc Currency] - [AME Billings].[Billings].[H1 Full Revenue Doc Currency]) for [Bill-to Customer Number],[Month],[Year])

And then in categories have the time period

And then in colors or series I have the promotions and discounts data items  .

When I run the report I am gettign an error

XQE-GEN-0005 Found an internal error:java unsupported operation

Will this be considered as a calculated member :
promotions :  [AME Billings].[Promo].[Promo Code] <> '' AND  [AME Billings].[Promo].[Non Promo Exclusion Flag] = ''
or how can i make this and discounts as 2 members .

Any suggestion on if what i am doing is correct for series and the measure .

Thanks,