Tag-it shows no delete-symbol

Tag-it shows no delete-symbol


I don't know why I don't get the "X" symbol ...
It should be like this:

How can I find the problem? Maybe an CSS-file is blocking an other CSS-file?
JavaScript-Code
$(function() {
var sampleTags = ['Klavier', 'Blockflöte', 'Schlagzeug', 'Gesang',
'Saxophon', 'Klarinette', 'Keyboard', 'Panflöte', 'Mundharmonika',
'Beatboxing', 'Akkordeon', 'Cello', 'Bratsche', 'Tuba', 'Kontrabass',
'E-Gitarre', 'E-Bass', 'Akustikgitarre'];
$('#singleFieldTags').tagit({
availableTags: sampleTags,
singleField: true,
singleFieldNode: $('#mySingleField'),
beforeTagAdded: function(evt, ui) {
var counter = jQuery.inArray(ui.tagLabel, sampleTags);
if(counter != -1) {
return true;
} else {
$('.tagit-new input').val('');
return false;
}
},
});
});