AspNetUsers cannot update custom column - asp.net

Question

So I have the problem with .net identity model. I created boolean variable IsEnabled in my ApplicationUserManager, trying to make a "block account" method. So it's working fine, anybody with IsEnabled=false cannot login in to my site. The problem is while Im trying to implement administartion method for this variable (Block_Account() for example) I cannot persist my changes in a user. Here is a code;
protected void Block_Click(object sender, EventArgs e)
{
string itemID;
using (GridViewRow row = (GridViewRow)((Button)sender).Parent.Parent)
{
HiddenField lUId = (HiddenField)row.FindControl("ClientId");
itemID = lUId.Value;
}
var user = Context.GetOwinContext().Get<ApplicationDbContext>().Users.Where(a => a.Email == itemID).FirstOrDefault();
//Label1.Text = user.UserName;
if (user.IsEnabled == true || user.IsEnabled == null)
{ user.IsEnabled = false; }
else { user.IsEnabled = true; }
Context.GetOwinContext().Get<ApplicationDbContext>().SaveChanges();
}
And another try
protected void Block_Click(object sender, EventArgs e)
{
string itemID;
using (GridViewRow row = (GridViewRow)((Button)sender).Parent.Parent)
{
HiddenField lUId = (HiddenField)row.FindControl("ClientId");
itemID = lUId.Value;
}
var manager = Context.GetOwinContext().GetUserManager<ApplicationUserManager>();
var user = manager.FindByEmail(itemID);
Label1.Text = user.UserName;
if (user.IsEnabled == true || user.IsEnabled == null)
{ user.IsEnabled = false; }
else { user.IsEnabled = true; }
manager.Update(user);
Context.GetOwinContext().Get<ApplicationDbContext>().SaveChanges();
}
Both not working actually.
So I got the right value from GridView and find a User with a right email, but after making changes, they wont appear in my database.