System Migration and Packages

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Hi,
I have a site created using 5.8.1 which I backed up prior to upgrading. When i installed this on another machine I found that the an extension Block which I had used - Webli Image Popup, doesn't appear on any of the pages. When I look in Extend Concrete5 it is installed and if I go into edit mode I can add it as a new blocks to an Area and it works fine.
Is there a setting I have missed?
Tks!