xwindows - attached calendar spawns javascript error

when the xwindow spawns i create a calendar attached to a inputbox, firebug spawns error:

wCal.con is undefined

/lib/codebase/dhtmlxcalendar.js

Line 50



this error spawns on ie8 and firefox.



when i open the web page shown in xwindow on a new explorer window there are no errors and has normal behaviour.



Thanks for your time.