Asp net web api token authentication

I'm using token authentication in my api, but when i test it in postman, it gives me an error 404 not found

(STARTUP.AUTH)

public partial class Startup
{
public static OAuthAuthorizationServerOptions OAuthOptions { get; private set; }
public void Configuration(IAppBuilder app)
{
app.UseOAuthBearerTokens(OAuthOptions);
}
static Startup()
{
OAuthOptions = new OAuthAuthorizationServerOptions
{
AccessTokenExpireTimeSpan = TimeSpan.FromDays(1),
AllowInsecureHttp = true,
TokenEndpointPath = new PathString("/token"),
Provider = new OAuthProvider()
};
}
}

(OAUTH PROVIDER)

public class OAuthProvider : OAuthAuthorizationServerProvider
{
public override Task GrantResourceOwnerCredentials(OAuthGrantResourceOwnerCredentialsContext context)
{
return Task.Factory.StartNew(() =>
{
string username = context.UserName;
string password = context.Password;
Usuarios user = new Usuarios().Get(username, password);
if(user != null)
{
List claims = new List
{
new Claim(ClaimTypes.Name , user.EmailUsuario),
new Claim("UserId", user.IdUsuario.ToString())
};
ClaimsIdentity OAuthIdentity = new ClaimsIdentity(claims, Startup.OAuthOptions.AuthenticationType);
context.Validated(new Microsoft.Owin.Security.AuthenticationTicket(OAuthIdentity, new Microsoft.Owin.Security.AuthenticationProperties() { }));
}
else
{
context.SetError("erro", "erro");
}
});
}
public override Task ValidateClientAuthentication(OAuthValidateClientAuthenticationContext context)
{
if(context.ClientId == null)
{
context.Validated();
}
return Task.FromResult<object>(null);
}
}

I have a user class with a list, but i guess that the problem isn't there.