Slicer problem with nulls

Hi guys,

I'd like to ask your advice, I have this scenario.

I have a table with Contract Number and Amount of Contract. Not all the contracts have an amount, this means there are no Invoices related to those contracts. The problem is I have a slicer of Year with a time dimension, this time dimension is driven by the Invoice date. So when I use the slicer the Contract Number # 101 will dissapear because the Invoice date is null, I was using the COALESCE function to show this Contract Number # 101, COALESCE(SUM(Amount of Contract),0) but this causes all the other slicers in the report become useless, because those will not filter anymore, will show all the rows, with amount 0. Any ideas on a workaround for the COALESCE?