maybe the code is missing from your forumhome template i think.

go to forumhome template and find

Code: 
<p>{vb:rawphrase most_users_ever_online_was_x_y_at_z, {vb:raw recordusers}, {vb:raw recorddate}, {vb:raw recordtime}}</p>
after that add

Code: 
<vb:if condition="$activeusers">
					<ol class="commalist" id="wgo_onlineusers_list">
						<vb:each from="activeusers" value="loggedin">
							<li> {vb:stylevar dirmark}<a class="username" href="{vb:link member, {vb:raw loggedin}}">{vb:raw loggedin.musername}</a>{vb:raw loggedin.invisiblemark}{vb:raw loggedin.buddymark}</li>
						</vb:each>
					</ol>
					</vb:if>