Oracle 8.0 Server Migration for Win NT 4.0

We tried to install Oracle Server 8.03 on Windows NT 4.0 with server pack 3 on a computer where a n Oracle WGS 7.3.2.3 is running and we wanted to migrate (means using the existing database with the tablespaces, data, ...) to become the new database.
In the manual (Oracle 8 Getting started for Windows NT) in chapter 5 database co-existence and migration the data migration dialog box (An earlier version of the database was detected. Would you like to migrate to 8.0.3.0.0?) is shown, which should follow in the installation sequence after the dialog box where you can select oracle 8, oracle 8 client, custom installation. When we start our installation, the Data Migration Dialogbox is skipped and not displayed.
What is going wrong with our setup?

Yours Sincerely

Manfred Tischendorf

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