The filter form on the top of the object admin page inherits the default properties, this can be problematic especially when you only want something to be display only.

When a property is set to display only, you are unable to filter by it.

To fix this modify the custom admin file as below.

<cfset stFilterMetaData = structNew() />
<cfset stFilterMetaData.thehiddenproperty.ftDisplayOnly= "false" />

<!--- set up page header --->
<admin :header title="News" />

<ft  bjectadmin  typename="dmNews"
permissionset="news"
title="#application.adminBundle[session.dmProfile.locale].newsAdministration#"
columnList="title,catnews,publishdate,datetimelastUpdated"
sortableColumns="title,publishdate,datetimelastUpdated"
lFilterFields="title,source"
stFilterMetaData="#stFilterMetaData#"
sqlorderby="publishdate desc"
plugin="farcrycms"
module="/dmNews.cfm" />

read more at http://docs.farcrycms.org/display/FCDEV40/Formtools+Object+Admin