I checked your site.

 

It works for me now.

 

Can you post your configuration file?

 

Please note that when you edit/create the configuration file, you should always put the dropdowns into a separate toolbar group:

 

<item type="g_start" />
  <item type="treedropdown" name="LinkTree" text="[[Links]]" width="50" command="InsertLink" />
  <item type="dropdown" name="Codes" width="65" RenderItemBorder="true" text="[[Codes]]" />
  <item type="dropdown" name="Images" width="50" RenderItemBorder="true" text="[[Images]]" />
  <item type="dropdown" name="Zoom" text="[[Zoom]]" width="50" command="Zoom" />
  <item type="g_end" />

 

Keep me posted