Cognos Analytics - Data Type Mismatch Error while using Aggregation

[Ria]

Hi,
I use this expression in my filter : [Date Added] = [Date Added - Min] ,[Date Added - Min] is  minimum([Date Added] for [Submission]). When I run view tabular data the query executes fine. But when I execute the report it fails with the data type mismatch error: UDA-EE-0094 The operation "equal" is invalid for the following combination of data types: "double" and "character"

Anyone got any suggestion? What am I doing wrong?

Thanks,
Ria.