Trouble creating a custom column in my gridview using C#

I have a DataTable that I am binding to a gridview.  The DataTable has two fields that are flags indicating the type of Title the record represents.  The first field is called IsMgr and the second IsSupervisor.  What I want my gridview to display is a column called Title Type and to display Manager if the IsMgr flag in the datatable is Y, Supervisor if the IsSupervisor flag in the datatable is Y otherwise display blank.

I thought I could do this in the RowCreated event but I can't access the data in the IsMgr and IsSupervisor colulmns.  (I added the fields from the datatable to the gridview as hidden fields).

Can someone please tell what I am doing wrong?

Here is my GridView markup:

            <asp:GridView ID="gvTitles" runat="server" CellPadding="5" 
                OnPageIndexChanging="gvTitles_PageIndexChanging" OnRowCancelingEdit="gvTitles_RowCancelingEdit"
                OnRowEditing="gvTitles_RowEditing" OnRowUpdating="gvTitles_RowUpdating"
                OnRowCreated="gvTitles_RowCreated"
                AlternatingRowStyle-BackColor="#0099CC" AlternatingRowStyle-BorderColor="Black" 
                AlternatingRowStyle-BorderStyle="Solid" AlternatingRowStyle-ForeColor="White" 
                AlternatingRowStyle-HorizontalAlign="Left" AlternatingRowStyle-VerticalAlign="Middle" 
                BorderStyle="Solid" HeaderStyle-BackColor="Silver" BorderColor="Black" 
                HeaderStyle-BorderColor="Black" HeaderStyle-BorderStyle="Solid" 
                HeaderStyle-HorizontalAlign="Center" HeaderStyle-VerticalAlign="Middle" 
                HorizontalAlign="Left" RowStyle-BorderColor="Black" RowStyle-BorderStyle="Solid" 
                RowStyle-HorizontalAlign="Left" RowStyle-VerticalAlign="Middle" 
                AutoGenerateColumns="False" 
                AutoGenerateEditButton="True"
                EmptyDataText="No Titles Found" AllowPaging="True">
                <AlternatingRowStyle HorizontalAlign="Left" VerticalAlign="Middle" BackColor="#0099CC" BorderColor="Black" 
                    BorderStyle="Solid" ForeColor="White"></AlternatingRowStyle>
                <HeaderStyle HorizontalAlign="Center" VerticalAlign="Middle" BackColor="Silver" BorderColor="Black" 
                    BorderStyle="Solid"></HeaderStyle>
                <RowStyle HorizontalAlign="Left" VerticalAlign="Middle" BorderColor="Black" BorderStyle="Solid"></RowStyle>
                <Columns>
                    <asp:BoundField DataField="TitleID" HeaderText="ID" ReadOnly="true" />
                    <asp:TemplateField HeaderText="Title">
                        <EditItemTemplate>
                            <asp:TextBox ID="tbEdit" runat="server" ToolTip="Title" Text='<%# Bind("TitleDesc") %>'
                                CssClass="TextBoxFormat" MaxLength="30"></asp:TextBox>
                            <asp:RequiredFieldValidator ID="tbTitleRequiredFieldValidator2" runat="server" 
                                ErrorMessage="Title is required" BackColor="Red" Font-Bold="True" ForeColor="White"
                                ControlToValidate="tbEdit" Display="Dynamic" validationgroup="Info"
                                Text="*"></asp:RequiredFieldValidator>
                        </EditItemTemplate>
                        <ItemTemplate>
                            <asp:Label ID="lblTitle" runat="server" Text='<%# Bind("TitleDesc") %>'></asp:Label>                       
                        </ItemTemplate>
                    </asp:TemplateField>
                    <asp:TemplateField HeaderText="Title Type">
                        <EditItemTemplate>
                            <asp:RadioButton ID="rbEdit0NonManagement" runat="server" Checked="True" GroupName="TitleType" Text="Non-Management" ToolTip="Non-Management Title Flag" ValidationGroup="Info" />
                            <asp:RadioButton ID="rbEditSupervisor" runat="server" Checked="False" GroupName="TitleType" Text="Supervisor" ToolTip="Supervisor Title Flag" ValidationGroup="Info" />
                            <asp:RadioButton ID="rbEditManager" runat="server" Checked="False" GroupName="TitleType" Text="Manager" ToolTip="Manager Title Flag" ValidationGroup="Info" />
                        </EditItemTemplate>
                        <ItemTemplate>
                            <asp:Label ID="lblTitleType" runat="server" Text=""></asp:Label>
                        </ItemTemplate>
                    </asp:TemplateField>
                    <asp:TemplateField HeaderText="Active">
                        <EditItemTemplate>
                            <asp:DropDownList ID="ddlStatus" runat="server">
                                <asp:ListItem Value="Y">ACTIVE</asp:ListItem>
                                <asp:ListItem Value="N">INACTIVE</asp:ListItem>
                            </asp:DropDownList>
                        </EditItemTemplate>
                        <ItemTemplate>
                            <asp:Label ID="lblStatusFlag" runat="server" Text='<%# Bind("ActiveStatusFlag") %>'></asp:Label>
                        </ItemTemplate>
                    </asp:TemplateField>
                    <asp:BoundField DataField="IsMgr" HeaderText="Manager" ReadOnly="true" Visible="False" />
                    <asp:BoundField DataField="IsSupervisor" HeaderText="Supervisor" ReadOnly="true" Visible="False" />
                </Columns>
            </asp:GridView>

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Here is my Code Behind for the RowCreated event (the Title Type column only displays blank and the e.Row.Cells[3].Text and e.Row.Cells[4].Text contain "")

        protected void gvTitles_RowCreated(Object sender, GridViewRowEventArgs e)
        {
            // Set TitleType based on value of IsMgr and IsSupervisor

            // Find the Title Type Label
            Label lbl = null;
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
                lbl = e.Row.FindControl("lblTitleType") as Label;

                // If title type is Manager, display Manager
                if (lbl != null && e.Row.Cells[3].Text == "Y")
                    lbl.Text = "MANAGER";
                // If title type is Supervisor, display Supervisor
                else if (lbl != null && e.Row.Cells[4].Text == "Y")
                    lbl.Text = "SUPERVISOR";
            }
        }

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lbl contains the cell for the Title Type column and if I hardcode a value using lbl.Text = "some value", the some value is displayed in the GridView.