How did you embed the messenger into your page?
Have you included IntegrationUtility.js.aspx into your page?
After adding the above script into your page, all you need to do is calling Chat_OpenMessengerDialog function.
Example:
<a href='###' onClick='Chat_OpenMessengerDialog()' >Messenger</a>
asp.net Chat http://cutesoft.net/ASP.NET+Chat/default.aspx
Web Messenger: http://cutesoft.net/Web-Messenger/default.aspx
asp.net wysiwyg editor: http://cutesoft.net/ASP.NET+WYSIWYG+Editor/default.aspx
asp wysiwyg html editor: http://cutesoft.net/ASP
asp.net Image Gallery: http://cutesoft.net/ASP.NET+Image+Gallery/default.aspx
Live Support: http://cutesoft.net/live-support/default.aspx