first item in listbox does not show in listbox

hi
I have a uerform with combo/textboxes and listbox ,if there is only one item listed it does not show in listbox although it does in textboxes,and does not pull image up in imagebox ,have added another item to the list and now it brings it up as should do,in combobox enter cooling towers,have left this second entry in,any ideas please have tried changing listbox to 1 and 0 but nothing seems to do it
cheers colin