Getting error

To call this method, the "Membership.Provider" property must be an instance of "ExtendedMembershipProvider". 

Line 99:                     if (!WebSecurity.UserExists(register.username)) 
Line 100:                    { 
Line 101:                        WebSecurity.CreateUserAndAccount(register.username, register.password, 
Line 102:                            new { FullName = register.FullName, EmailID = register.EmailID }); 
Line 103:                        Response.Redirect("~/account/login");

below is my register method 
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Register(Register register, string actionType)
{
if (actionType == "Save")
{
if (ModelState.IsValid)
{
if (!WebSecurity.UserExists(register.username))
{
WebSecurity.CreateUserAndAccount(register.username, register.password,
new { FullName = register.FullName, EmailID = register.EmailID });
Response.Redirect("~/account/login");
}
}
else
{
ModelState.AddModelError("Error", "Please enter all details");
}
return View();
}
else
{
return RedirectToAction("Index");
}
}
How to solve it
below is my config file