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Cannot set primary key of table using PowerDesigner

To set one or multi properties whose names are used in several tables will be failed, responding the following message in a popup dialog:

If several tables contain same property, which is respected to set as primary
This data item is already used in a primary identifier. 
Normalization rules prevent from reusing this data item in another entity.  

Then you can check off the feature:
Tools -> Model Options -> Model Settings -> Data Item -> Unique code

The third section of this page also mentions this issue, what's more, it contains an illustrator which I link for this page.