fail to create an attribute view

Hello,

I would like to create an attribute view by joining two tables:

Table:Customers

Key:RowID

Attribute:CustomerID

Table:CustomersKeys

Key:CustomerID

Key:SourceSystem

Key:SourceKey

I join the two tables on the CustomerID key attribute, and receive the following error:

MDXRuntime: Internal deployment of object failed: Internal Error:Error occurred during deployment. The error message is: exception 1: no.1000014 (mdx/metadata/deployment/dmo/DMODimension.cpp:134)n Central table not unique.

Two key attributes found for different tables.

Any idea what is wrong.

-Ronen