Forms Data Controls :: CheckBox In DataGrid Doesn't Work

I am making checkbox in datagrid, no matter what I try, I cannot get the right result from checkbox. Even I check or not check the checkbox, the result is false. It is like somehow the result is always the default value of the checkbox.

Here is code:

private void OrderButton_Click(object sender, System.EventArgs e)
{
CheckBox x;
foreach ( DataGridItem dgItem in DataGrid1.Items)
{
x = (CheckBox)dgItem.FindControl("OrderCheckBox");
this.ALERT(x.Checked.ToString());
}
}

And here is my html:

[Code]....