When adding a new table to an existing dimension, the test results show no data being returned.
NULL values where data is expected
Two tables were being joined on a VARCHAR field. However, in one table, the field was described as VARCHAR(4) and the other it was a VARCHAR(1).
SQL Server 2008 R2 source database
Diagnosing the problem
Individually, each table contained data and select statements show that the columns have similar values.
Resolving the problem
Cast the VARCHAR(1) field to a VARCHAR(4) field so that the join will succeed and data will be returned.