You have to add wp_register_activation and deactivation hooks to replace old ones, and even when you do (which then lets you activate the plugin), you still can't authenticate it with Flickr.
If you put in your API and Secret, it brings up an authentication button, but if you click it, you get a weird Apache cpanel test page and no authentication.
Strange stuff. Was a good plugin at one point but it's no longer supported by the author and it doesn't work reliably. Time to find something else!