NullProcessing on Dimension keys

Running in to the following problem

Have a dimension (time dimension) with a datetime keyfield. Have a fact table with a date field that is sometimes not filled in. A regular relationship exists in the dimension usage tab between this time dimension and the measure group of the fact table based on the date field.

So I set up the time dimension with dimesion property UnknownMember visible, set the NullProcessing property of the keyColumn of the dimension keyfield (you're still folowing ;-) to UnknownMember because I want to avoid the default beheaviour of SSAS making it 0 or blank.

Deploy the thing and get the following 2 warnings:

Warning 1 Errors in the OLAP storage engine: The attribute key cannot be found: Table: dbo_ProjectCard, Column: ProjectDateSold, Value: 0:00:00. 0 0
Warning 2 Errors in the OLAP storage engine: The attribute key was converted to an unknown member because the attribute key was not found. Attribute Time of Dimension: Project Sold Date from Database: CDWH OLAP database, Cube: CDWH, Measure Group: Project Card, Partition: Project Card, Record: 8. 0 0

Both of them seem perfectly normal (Notice that the value of warning 1 represents the NULL date) and that warning 2 actualy tells me that it was converted to an unknown member, but then I get 3 errors

Error 3 Errors in the OLAP storage engine: The process operation ended because the number of errors encountered during processing reached the defined limit of allowable errors for the operation. 0 0
Error 4 Errors in the OLAP storage engine: An error occurred while processing the 'Project Card' partition of the 'Project Card' measure group for the 'CDWH' cube from the CDWH OLAP database database. 0 0
Error 5 Errors in the OLAP storage engine: The process operation ended because the number of errors encountered during processing reached the defined limit of allowable errors for the operation. 0 0

So it seems that's no good, This works perfect for dimension attributes but what am I missing here ?

Tx /Dirk

Found the solution

In the dimension usage tab, when you define the relationship. You can click the advanced button. In this dialog you can also modify the NullProcessing. So you need to set it here to UnknowMember instead of keyColumn of the dimension itself.

Wished MS would make it more consistent.