Errors occured in the attribute view

Hi

I have created two tables with the name Material_01 and Material_02 with the field name as Material_ID and Material_Name.

While creating the attribute view I have set the join based on the Material_ID from both the tables

When i Click on the Save and Validate icon I do get an error. can any one let me know how to resolve this issue??

Thanks and regards

Sanjay