Hi there,
you are mixing two transformation codes together (ASCX and Text/XML). If the title works you are using the ASCX type, so you need to stick with the <%# %> syntax:
<item>
<title><%# Eval("ContentTitle") %></title>
<link><%# Eval("AliasURLPath") %></link>
<description><%# Eval("Summary") %></description>
<pubDate><%# Eval("DocumentPublishFrom") %></pubDate>
<guid><%# Eval("NodeGUID") %></guid>
</item>