Last Fact Date in report

[svenv]

I am creating a sales report in Report Studio on Cognos 8.3.
I have 1 time dimension in the report, and a dimension "Customer Type", and various other dimensions.
I also have various measures, including "Sell-Out Quantity".

In the report footer, I want to display the most recent date that has a value for the "Sell-Out Quantity" measure" for "Retail Customers" on the "Customer Type" dimension.

My initial idea was to use "Set Current Period" on the datasource in transformer and then the "Current Date" special time category on the report, but this can not be done, because I do not want my cube's "Current Period" to be influenced by retail sales ONLY.
How do I add this (scalar) to my report?

Thanks a lot in advance!

[billylodz]

I have additional dimension with cube creation date and one member inside, (simple getdate() in query).

[svenv]

Great, thanks!