In prosilver, we can see that code in mcp_post.html

 <!-- IF SIGNATURE --> <!-- IF SIGNATURE --> <div id="sig{POST_ID}" class="signature">{SIGNATURE}</div> <!-- ENDIF -->

However, the {SIGNATURE} template variable is defined only in...

• includes\acp_users.php
• includes\ucp_pm_viewmessage.php
• includes\ucp_profile.php
• memberlist.php
• viewtopic.php

... and nowhere in the Moderator Control Panel (MCP) !

Consequently, the code in mcp_post.html is useless.

You should either define {SIGNATURE} in MCP-related php files or remove the code in mcp_post.html