can not find default member (Dimension,Attribute) in cube

Hey!

I have a problem in processing a cube.

I get the following error and have no idea why the cube can't find the "all"-element.

"DefaultMember (<Dimension>,<Attribute>) (1,1) The [All]-Element can't be found by analyzing the string '[Dimension].[Attribute].[All]' in the cube."

I have set the property IsAggregatable to True. I also added the following MDX-Expression

ALTER CUBE CurrentCube | YourCubeName UPDATE DIMENSION <dimension name>, DEFAULT_MEMBER='<default member>'; in my calculations

because i am using the dimension 3 times with different names in the cube.

Does anybody have a suggestion how to solve this problem?