Entity Framework does not create database - entity-framework

Question

I try to implement Entity Framework Code First method. I have two class which are Student and Standard(Grades). This is my Standard model:
class Standard
{
public Standard()
{
}
public int StandardId { get; set; }
public string StandardName { get; set; }
public ICollection<Student> Students { get; set; }
}
and Student model:
class Student
{
public Student()
{
}
public int StudentID { get; set; }
public string StudentName { get; set; }
public DateTime? DateOfBirth { get; set; }
public byte[] Photo { get; set; }
public decimal Height { get; set; }
public float Weight { get; set; }
public Standard Standard { get; set; }
}
Context:
class SchoolContext : DbContext
{
public SchoolContext() : base()
{
}
public DbSet<Student> Students { get; set; }
public DbSet<Standard> Standards { get; set; }
}
App config:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
<!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
<section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
</configSections>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2" />
</startup>
<entityFramework>
<defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
<parameters>
<parameter value="(LocalDb)\MSSQLLocalDB" />
</parameters>
</defaultConnectionFactory>
<providers>
<provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
</providers>
</entityFramework>
</configuration>
and main method:
class Program
{
static void Main(string[] args)
{
using (var ctx = new SchoolContext())
{
ctx.Database.Initialize(force:true);
Student stud = new Student() { StudentName = "New Student" };
ctx.Students.Add(stud);
ctx.SaveChanges();
}
}
}
It compiles and runs but the database does not exist. Where do I make wrong ?