In Umbraco 7 I've set up a datatype on the property editor Umbraco.MultipleTextstring. This field is supposed to be an array of strings. When I try to retrieve the contents of this field HasValue is true, but the length of the array is zero. I'm unable to retrieve the content through

@foreach (var item in promotion.listItems)
{
     <li>@item</li>            
}

The only way I've been able to retrieve the content so far is by using

var contentService = ApplicationContext.Current.Services.ContentService;
var content = contentService.GetById(promotion.Id);

@content.GetValue("listItems")

Can anyone help me out here?