Hi,
Seems the problem is that you’re initializing the options for combobox without value:
$('select[name="combobox1"]').append( new Option("peter pan 2") );
Try this and let me know how it goes:
$('select[name="combobox1"]').append( new Option("option 1","1") );
$('select[name="combobox1"] option[value="1"]').attr('selected','selected')