ASP.Net MVC DllImport BadImageFormatException 32bit/64bit

我有下面的代码，它正在抛出一个BadImageFormatException。它正在加载的DLL是32位的。web服务器运行的是Windows 64位，但应用程序池设置为"启用32位"。有什么办法让它发挥作用吗？

public class HomeController : Controller
{
    [DllImport("CDCrypt.dll")]
    [return: MarshalAs(UnmanagedType.LPStr)]
    public static extern String Encrypt 
        ([MarshalAs(UnmanagedType.LPStr)] String aName);
    [DllImport("CDCrypt.dll")]
    [return: MarshalAs(UnmanagedType.LPStr)]
    public static extern String Decrypt
        ([MarshalAs(UnmanagedType.LPStr)] String aName);
    public ActionResult Index()
    {
        try
        {
            ViewBag.EncryptString = Encrypt("test");
        }
        catch (Exception e)
        {
            ViewBag.EncryptString =
                "Stack Trace'r'n:" + "'r'nException: " + e.Message;
            return new HttpStatusCodeResult(500);
        }
        return View();
    }
    public ActionResult Up()
    {
        ViewBag.Up = "You can see me";
        return View();
    }
}