Trebuchet error

You received the following error:
invalid command name ".mw.selector1.listbox"
    while executing
"$base.listbox nearest 0"
    (procedure "selector:update" line 2)
    invoked from within
"selector:update .mw.selector1 {/world names} update furryMUCK"
    ("eval" body line 1)
    invoked from within
"eval "$WorldInfo($key) [list $type] [list $name]""
    (procedure "/world:notifyregistered" line 4)
    invoked from within
"/world:notifyregistered update $name"
    (procedure "/world:add" line 22)
    invoked from within
"/world:add $WorldInfo($master,gui,name)  $WorldInfo($master,gui,host)  $WorldInfo($master,gui,port)  $WorldInfo($master,gui,char)  $WorldInfo($master,..."
    (procedure "/world:widgets:mknode" line 20)
    invoked from within
"/world:widgets:mknode .mw.newdlog1.client"
    ("eval" body line 1)
    invoked from within
"eval "$cmd""
    (procedure "dispatcher" line 7)
    invoked from within
"dispatcher /world:widgets $opt $args"
    (procedure "/world:widgets" line 2)
    invoked from within
"/world:widgets mknode .mw.newdlog1.client"
    ("eval" body line 1)
    invoked from within
"eval "$cmd""
    (procedure "dispatcher" line 7)
    invoked from within
"dispatcher /world $opt $args"
    (procedure "/world" line 2)
    invoked from within
"/world widgets mknode .mw.newdlog1.client"
    invoked from within
".mw.newdlog1.buttons.add invoke"
    ("uplevel" body line 1)
    invoked from within
"uplevel #0 [list $w invoke]"
    (procedure "tk::ButtonUp" line 23)
    invoked from within
"tk::ButtonUp .mw.newdlog1.buttons.add"
    (command bound to event)