ActiveScaffold - custom show action

Hi all,
I've added custom show action (as an action link - I want to use default
one too). Everything renders well, but I'm missing a "Close" ([x])
button. So, I copied AS' default _show.rhtml template and edited it a
bit (just added custom output and removed label). However, when I click
at "Close" I get error output:

You have a nil object when you didn't expect it!
The error occurred while evaluating nil.theme

<div id="<%= active_scaffold_id -%>" class="active-scaffold
active-scaffold-<%= controller_id %> <%= active_scaffold_config.theme
%>-theme">

Why is active_scaffold_config nil?

Thank you for any help.