Trouble redirecting after login

Not sure what's happening here, I've verified the login code below runs correctly but i cannot redirect to any page...it always goes back to the login page.  I've run this on Chrome and Safari - same results.

public ActionResult Login(LoginModel model, string returnUrl)
{
    if (ModelState.IsValid && WebSecurity.Login(model.UserName, model.Password, persistCookie: model.RememberMe))    {return RedirectToLocal(returnUrl);
       //return RedirectToAction("Index", "Home");
    } ...

<authentication mode="Forms"><forms loginUrl="~/Account/Login" timeout="2880" cookieless="UseCookies"/></authentication>

Fiddler shows that a cookie is being set and passed on the next request but it seems like it's being ignored. Any ideas on what might be happening?

Thanks

Tim