Artweb-design adva cms

When try to search for an asset from the "search" tab of the asset widget, an exception is raised by the server:

ActionView::TemplateError (undefined local variable or method `content' for #<ActionView::Base:0x32d8ff4>) on line #1 of vendor/plugins/adva_assets/app/views/admin/assets/widget/_asset.html.erb:
1: <li id="<%= dom_id(asset, prefix) %>" class="asset <%= prefix %>_asset <%= ' selected' if content and content.assets.include?(asset) %>">
2:   <%= link_to asset_image_for(asset), asset.base_url %>
3:   <div>
4:     <a href="#"><%= image_tag('/images/adva_cms/icons/add.png', :size => '16x16', :id => dom_id(asset, "attach_#{prefix}"), :style => 'display:none', :class => 'attach_asset') %></a>

    vendor/plugins/adva_assets/app/views/admin/assets/widget/_asset.html.erb:1
    vendor/plugins/adva_assets/app/views/admin/assets/index.rjs:2:in `__instance_exec0'
    vendor/plugins/adva_assets/app/views/admin/assets/index.rjs:1:in `_run_rjs_vendor47plugins47adva_assets47app47views47admin47assets47index46rjs'
    vendor/plugins/adva_assets/app/controllers/admin/assets_controller.rb:13:in `index'