问无点引擎分析器返回空字符串？

var bootstrapStyles = new Bundle("~/bundle/style/bootstrap").Include("~/Content/less/*.less");
bootstrapStyles.Transforms.Add(new LessTransform());
bootstrapStyles.Transforms.Add(new CssMinify());
bundles.Add(bootstrapStyles);

var parsedLess = Less.Parse(bundle.Content);
bundle.Content = parsedLess;

// Throws a FileNotFoundException
// "You are importing a file ending in .less that cannot be found."
// reset.less and it definitely exists in that folder. 

var content = new StringBuilder();
var engine = new LessEngine();

foreach (var file in bundle.Files)
{
    // text is extracted correctly.
    var text = File.ReadAllText(file.FullName);
    // transform function returns an empty string, no errors
    var css = engine.TransformToCss(text, file.FullName);
    content.AppendLine(css);
}
bundle.Content = content.ToString();