On a 32 bit OS, the Photozoom 4/6 installer creates an unncessary folder ..\Program Files (x86)\Corel\Plugins
It should be installing to the ..\Program Files\Corel\Plugins folder
1. Create a folder ...\Program Files\Corel\Plugins and move the content from ..\Program Files (x86)\Corel\Plugins to this newly created folder, ...\Program Files\Corel\Plugins
2.In PHOTO-PAINT, go to Tools > Options > Plug-ins and select Add.., navigate to the folder ...\Program Files (x86)\Corel\Plugins to add it manually.
Either method will resolve the problem.