You cannot reuse a workspace that was created with a previous version of the product.
Rational® Programming Patterns V9.0.1 cannot run with the VisualAge® Pacbase data that was migrated from a previous version. So, you must run the VisualAge Pacbase 3.5 Y09B extraction and migration procedures.
Then, you must create a V9.0.1 workspace to import the data.