I have a strange problem with the configuration of some of my plugins in the admin panel. Most of them show a correct detail page after choosing the plugin from plugin configuration in admin panel.
But some of them:
* serendipity_html_nugget_plugin
* serendipity_event_contactform
* serendipity_event_head_nugget
show only a part of the detail page. The configuration-content of the plugin is shown, but everything else, the header, the footer, the sidebar of admin panel and all style sheets are gone. Also there is no "save"-Button.
A quick look in the html-code shows, that the code is incomplete. What could I do?
Here is a screenshot of the working plugin:

Here is a screenshot of the broken plugin:
