GridView DataBind does not work - asp.net

Question

I am using ASP.NET Membership and Linq. I have a problem here: I show all users inside a grid view that has a delete button. Take a look at this code:
<asp:GridView
ID="UsersGridView"
runat="server"
AutoGenerateColumns="False"
DataSourceID="UsersLinqDataSource"
AllowPaging="True">
<Columns>
<asp:BoundField DataField="UserName" HeaderText="UserName" ReadOnly="True" SortExpression="UserName" />
<asp:BoundField DataField="LastActivityDate" HeaderText="LastActivityDate" ReadOnly="True" SortExpression="LastActivityDate" />
<asp:TemplateField>
<ItemTemplate>
<asp:Button ID="DeleteButton" runat="server" CommandArgument='<%# Eval("UserName") %>' Text="Delete" OnClick="DeleteButton_Click"/>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
<asp:LinqDataSource
ID="UsersLinqDataSource"
runat="server"
ContextTypeName="TraceWeb.DataModel.DataContextDataContext"
EntityTypeName=""
Select="new (UserName, LastActivityDate)"
TableName="Users"
EnableDelete="True">
</asp:LinqDataSource>
And Delete button's event handler:
protected void DeleteButton_Click(object sender, EventArgs e)
{
String username = (String)((sender as IButtonControl).CommandArgument);
Membership.DeleteUser(username, true);
UsersGridView.DataBind();
}
But problem is that after running this code and deleting a user, GridView still shows that user.

Answer 1

This happens because Membership and UsersLinqDataSource are not connected and if you "refresh" the UsersLinqDataSource status and then rebind your grid, all will be displayed properly.
protected void DeleteButton_Click(object sender, EventArgs e)
{
String username = (String)((sender as IButtonControl).CommandArgument);
Membership.DeleteUser(username, true);
// first solution: may not work properly
UsersLinqDataSource = yourLinqData;
// second solution: work
UsersLinqDataSource = null;
UsersLinqDataSource = yourLinqData;
UsersGridView.DataBind();
}