CheckBox just Checked in the second click c# GridView

Background: The problem i have with my code is the following, upon click a button the checkbox doesn't get the checked checkboxes, but in the second click just get all the checked checkboxes.

Here the code:

ASPX This button execute the process..

<asp:LinkButton ID="lbDeletePerman" runat="server" OnClick="lbDeletePerman_Click">Yes</asp:LinkButton>

            <asp:GridView CssClass="da-table" ID="Gv_A" runat="server" DataKeyNames="ID,PatientName" AutoGenerateColumns="false" OnRowCommand="Gv_Appoint_RowCommand">
                <Columns>
                    <asp:TemplateField HeaderStyle-Font-Bold="true" HeaderText="Select">
                        <ItemTemplate>
                            <asp:CheckBox ID="CbE" runat="server" />
                            <asp:HiddenField ID="hID" Value='<%# Eval("IDENTIFICATION") %>' runat="server" />
                        </ItemTemplate>
                    </asp:TemplateField>

                    <asp:BoundField DataField=""Date" HeaderText="Date" HeaderStyle-Font-Bold="true" HeaderStyle-VerticalAlign="Middle" ItemStyle-VerticalAlign="Middle" />

                    <asp:BoundField DataField="Cat" HeaderText="Type" HeaderStyle-Font-Bold="true" HeaderStyle-VerticalAlign="Middle" ItemStyle-VerticalAlign="Middle" />
                    <asp:BoundField DataField="Deleted" HeaderText="Deleted" HeaderStyle-Font-Bold="true" HeaderStyle-VerticalAlign="Middle" ItemStyle-VerticalAlign="Middle" />
                </Columns>
            </asp:GridView>

        </ContentTemplate>
    </asp:UpdatePanel>

C#:

protected void lbDeletePerman_Click(object sender, EventArgs e)
{
    try
    {

        foreach (GridViewRow rowItem in Gv_Appoint.Rows)
        {
            CheckBox CboxElim = (CheckBox)(rowItem.Cells[0].FindControl("CbDelApprst")); 
            if (CboxElim.Checked)
            {
                LBLT.Text = "Hello"; // NO ENTERING HERE
            }

        } 
        GVUpdatePanel.Update();
    } catch (Exception er){}
}

Will be appreciated whatever help.