Gridview paging not loading second page

Very new to C# ASP.Net here, and trying to display a gridview populated with database data. The dataset is large, and I want to add paging to the view. Unfortunately when I follow instructions I found online, only the initial page loads. When I click on the second page, the gridview disappears.
Here's the page source:

<%@ Page Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="Home.aspx.cs" Inherits="Araya_Web.Home" %>

<asp:Content ID="Content1" runat="server" contentplaceholderid="MainContent">
    <br />
    <asp:GridView ID="gridProjects" HeaderStyle-BackColor="#3AC0F2" HeaderStyle-ForeColor="White" Width="100%" AllowPaging="true" AllowSorting="true"
        PageSize="25" runat="server" AutoGenerateColumns="true" OnPageIndexChanging="gridProjects_PageIndexChanging" ShowHeaderWhenEmpty="true">

<HeaderStyle BackColor="#3AC0F2" ForeColor="White"></HeaderStyle>
        <PagerSettings FirstPageText="First" LastPageText="Last" Mode="NumericFirstLast" />

</asp:GridView>
    <br />
</asp:Content>

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and here's the code-behind:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Data;
using System.Web.Configuration;

namespace Araya_Web
{
    public partial class Home : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                string strQuery = "Select p.project_id as 'ID', p.project_name as 'Name', u.full_name as 'Created by', p.create_date as 'Created on' " +
                    "From PCR_Projects p inner join UserList u on p.created_by = u.user_id order by p.project_id";
                SqlCommand cmd = new SqlCommand(strQuery);
                DataTable projects = getData(cmd);
                gridProjects.DataSource = projects;
                gridProjects.DataBind();
            }

        }

        protected DataTable getData(SqlCommand cmd)
        {
            using (SqlConnection con = new SqlConnection(WebConfigurationManager.ConnectionStrings["EWSDB"].ConnectionString))
            {

                // Create data table to hold project info
                DataTable dt = new DataTable();
                SqlDataAdapter sda = new SqlDataAdapter();
                cmd.CommandType = CommandType.Text;
                cmd.Connection = con;

                // Connect to database and fetch all project ID's and names.
                try
                {
                    con.Open();
                    sda.SelectCommand = cmd;
                    sda.Fill(dt);
                    return dt;
                }
                catch (Exception ex)
                {
                    string msg = "Fetch Error:";
                    msg += ex.Message;
                    throw new Exception(msg);
                }
                finally
                {
                    con.Close();
                    sda.Dispose();
                    con.Dispose();
                }
            }
        }
        protected void gridProjects_PageIndexChanging(object sender, GridViewPageEventArgs e)
        {
            gridProjects.PageIndex = e.NewPageIndex;
            gridProjects.DataBind();
        }
    }
}

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Can anyone tell me why my gridview isn't just showing the second page? Do I need to do something with the ViewState? I'd prefer not to add custom paging, as I plan to add filters to the table next which will complicate the SQL if custom paging is required. I'm using Visual Studio 2012, ASP.Net 4.5.