C# - Gridview FooterRow Textbox Text Is Null When Accessing From Code Behind

I have a GridView with the following columns

<asp:TemplateField HeaderText="Name">
<FooterTemplate>
<asp:TextBox ID="txt_Name" runat="server"></asp:TextBox>
</FooterTemplate>
<ItemTemplate>
<asp:Label ID="lbl_name" runat="server" Text='<%# DataBinder.Eval(Container.DataItem, "t_Name") %>' />
</ItemTemplate>
<EditItemTemplate>
<asp:TextBox ID="txt_name" runat="server" Width="100px" Text='<%#DataBinder.Eval(Container.DataItem,"t_Name") %>'></asp:TextBox>
</EditItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Created By">
<ItemTemplate>
<asp:Label ID="lbl_tabcreatedby" runat="server" Text='<%# DataBinder.Eval(Container.DataItem, "t_CreatedBy") %>' />
</ItemTemplate>
</asp:TemplateField>
<asp:CommandField HeaderText="Modify" ShowEditButton="True" />
<asp:CommandField HeaderText="Delete" ShowDeleteButton="True" />
<asp:TemplateField HeaderText="Add a New Name">
<FooterTemplate>
<asp:LinkButton ID="lnkbtn_AddName" runat="server" CommandName="Insert">Add Name</asp:LinkButton>
</FooterTemplate>
</asp:TemplateField>

And then in the Code Behind I am trying to access the txt_Name Textbox as

protected void gv_Name_RowCommand(object sender, GridViewCommandEventArgs e)
{
string t_Name = ((TextBox)(gv_Name.FooterRow.FindControl("txt_Name"))).Text;
// Insert Code
}

But I am getting null in the string t_Name everytime irrespective of what is the current Text of txt_Name.
However I can get the text if I disable the ViewState for the page.