Time mask with iMask

I'm using this Jquery plugin to format masks but I can not do the same to work, even religiously following the existing example , I tried this by changing an existing format for my case:

$(document).ready(function() {
    $('#dHora').iMask({
          type      : 'fixed'
        , mask      : '00:00'
        , stripMask : true
    })  
});

But the mask is not applied.