CSS merge issue when publishing an ASP.NET MVC application

Question

I am trying to publish an ASP.NET MVC 5 application on a local network server. The CSS files that were included in my Layout view were not found (the package definition in bundleConfig.cs is

bundles.Add(new StyleBundle("~/Content/css").Include(
                      "~/Content/bootstrap.css",
                      "~/Content/site.css"));

) when I replace @Styles.Render("~/Content/css")
 with

<link href="~/Content/bootstrap.css" rel="stylesheet" />
<link href="~/Content/Site.css" rel="stylesheet" /> 

it works.