An error has occurred

Thankyou for your help

Details of the error are as follows:
SQL Error:
select filename+'.asp:'+name+':'+isnull(classname,'menu')+':'+isnull(anchor,'') from conferencemenulang inner join conferencemenu on conferencemenulang.conferencemenuid=conferencemenu.conferencemenuid where langid='en' and conferencemenu.conferenceid=undefined and published=1 order by [order]
Invalid column name 'undefined'.