Do you ever get this error:

• Warning 5 Errors in the OLAP storage engine: The attribute key cannot be found when processing: Table: ”, Column: ”, Value: ’12:00:00 AM’. The attribute is ‘Date’.

It turns out that this error occurs because:

• Null values in the fact table relationship are converted to ’12:00 A.M.’

So I tried enabling the Unknown Member attribute of the Date table.  (It’s a standard Date table generated by the SSAS wizard for such things.)

No luck.  Still getting the error when the date in the Fact table is null.

It turns out that enabling the Unknown Member is a multi-step process.   (Much thanks to wildh for their post here.)

To enable the Unknown Member on a Dimension follow these steps:

1. Go to the Properties Page of the Date Dimension you are using, and select UnknownMember visible AND set the UnknownMemberName to something, such as ‘Unknown’:

   

   Enable the Unknown Member in the Dimension

2. Now, go to the Cube Definition and click on the Dimension Usage tab:

   

3. Next, click on the button next to the Date dimension usage, and then click the advanced button in the bottom right:

   

4. Finally, change the relationship Null Processing drop down to Unknown Member:

   

5. Click OK. To get back to the Dimension Usage tab, and change the Null Processing dropdown for any other Date relationship where the date in the Fact table could be null.