Problem with comboBox

 Hi, i'm making my first graphic interface program with Haskell. I use
Glade and Gtk+2.0. I create an empty comboBox with Glade and I want to
add items (strings) in run time (by means of the haskell code). I
tried with the functions 'comboBoxAppendText' and 'comboBoxInsertText'
(http://haskell.org/gtk2hs/docs/current/Graphics-UI-Gtk-MenuComboToolbar-ComboBox.html#t%3AComboBox)
but I can not do anything for display the information I want. This
functions require to work with a comboBox creates with the constructor
comboBoxNewText (and I think this constructor is not the used by
Glade). I can create it from Glade? I can do I want by another method?
Thanks.