[delicjous]

You have to edit the code to:

<vb:if condition="!empty($conversation['userid'])">
{vb:data userInfo, user, fetchProfileInfo, {vb:raw conversation.userid}}
<br />
<vb:if condition="$userInfo['field10'] == 'yes'"><li><span style="color: red;"><label>{vb:phrase field10_title}</label></span></li></vb:if> 
</vb:if>

Because the first code will output an error.
For more info look here: http://tracker.vbulletin.com/browse/...s:all-tabpanel

Thanks to Sebastiano Vassellatti and the developer who helped him!