entities.SaveChanges（）未保存到db

Question

我在EF中尝试一个简单的程序，将一个玩家从gridview添加到团队中。代码似乎一直有效，直到savechanges部分。从其他帖子来看，我的代码存在问题，但我看不清楚。

protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
{
    int v = Convert.ToInt32(GridView1.SelectedIndex);
    int pId = Convert.ToInt32(GridView1.DataKeys[v].Value);
    chosenPlayer = entities.Players.Find(pId);
    int noPlayers = myTeam.Players.Count();

    if (noPlayers < 5)
    {
        myTeam.Players.Add(chosenPlayer);
    }
    entities.SaveChanges();
    RefreshGrid();
}