.SaveChanges not applying changes to database in entity framework

I'm trying to use the code below to add an entry in the 'UserAlertSubscriptions' table in my db which just links users to alertconfigurations.

The problem is that although i get no errors the entry does not get added to the database.

Any idea what i'm doing wrong. As you can see, I tried ApplyAllChanges, but this made no difference.

AlerterDataEntities alerterDataEntities = new AlerterDataEntities()

// get current user
User user = alerterDataEntities.Users.Where(u => u.UserID == 1).ToList<User>()[0];

// get selected alert configuration
AlertConfiguration alertConfiguration =
    alerterDataEntities.AlertConfigurations.Where(a => a.AlertConfigurationID == 3).ToList
        <AlertConfiguration>()[0];

UserAlertSubscription userAlertSubscription = new UserAlertSubscription
{
    User = user,
    AlertCo开发者_开发知识库nfiguration = alertConfiguration
};

user.UserAlertSubscriptions.Add(userAlertSubscription);
//alerterDataEntities.AcceptAllChanges();
alerterDataEntities.SaveChanges();

All fixed - I found the problem was that the database was being copied to the output directory each time I ran it. So the table I was looking at (the one in the root of my application) was not the one it had added to.

This post solved by @Jean-Lois was where I found the solution: C# Entitity framework SaveChanges() not working

To solve it I set the database 'Copy to output directory' to 'Do not copy' and put the full file path in the database connection string in the app.config