Reposting my answer from DAZ forum :-

If the import plugin you mentioned is the TurboImporter, then you don't need that because Bryce 5.5 as the same functionality is built-in.

You'll need to uninstall both Bryce and the plugin, then just reinstall Bryce.

(If you take another look in the Bryce folder you should see that you have B55Axiom.dll which comes with Bryce 5.5 not B5Axiom.dll which came with Bryce 5 and is the one the plugin is looking for).