Forms Data Controls :: GridView - Unable To Update The Text In A Row

i'm unable to update a row in a gridview, Actually everything is fine but when i'm entering some new text in the textbox and if i press update control, it still shows me the previous text, it is not updating and it doesn't write into XML either.

Here is my design:

[Code]....

Here is my Code:

protected void Page_Load(object sender, EventArgs e)
{
showupdates();
GridView1.DataBind();
}
protected void Button1_Click1(object sender, EventArgs e)
{
if (TextBox1.Text != "")..........