Problem with javascript code and content page

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ASP.NET

i write javascript code for aspx page that time it works but when i used this javascript code in content page that time it's not working properly..what should i do?

script code:

<script type="text/javascript">
    var SelectedRow = null;
    var SelectedRowIndex = null;
    var UpperBound = null;
    var LowerBound = null;

    window.onload = function()
    {
        UpperBound = parseInt('<%= this.GrdATDataView.Rows.Count %>') - 1;
        LowerBound = 0;
        SelectedRowIndex = -1;
    }

    function SelectRow(CurrentRow, RowIndex)
    {
        if(SelectedRow == CurrentRow || RowIndex > UpperBound || RowIndex < LowerBound) return;

        if(SelectedRow != null)
        {
            SelectedRow.style.backgroundColor = SelectedRow.originalBackgroundColor;
            SelectedRow.style.color = SelectedRow.originalForeColor;
           //TextBox1.Text = GrdATDataView.SelectedRow.Cells[1].Text;
        //document.getElementById('TextBox1').value=GrdATDataView.rows[SelectedRowIndex].cells[1].innerText;
        //var sohil = document.getElementById(RowIndex).value;


        if(CurrentRow != null)
        {
            CurrentRow.originalBackgroundColor = CurrentRow.style.backgroundColor;
            CurrentRow.originalForeColor = CurrentRow.style.color;
            CurrentRow.style.backgroundColor = '#DCFC5C';
            //var grid = document.getElementById('<%=GrdATDataView.ClientID%>');
            //var cell = grid.rows[0].cells[5].innerText;
           // var Row = GrdATDataView.getAttribute("rel");


         document.getElementById('TextBox1').value=GrdATDataView.rows[RowIndex+1].cells[1].innerText;
            CurrentRow.style.color = 'Black';
            // TextBox1.Text = GrdATDataView.SelectedRow.Cells[1].Text;


        }

        }

        SelectedRow = CurrentRow;
        SelectedRowIndex = RowIndex;
        setTimeout("SelectedRow.focus();",0);

    }//TextBox1.Text = GridView1.SelectedRow.Cells[1].Text;

    function SelectSibling(e)
    {
        var e = e ? e : window.event;
        var KeyCode = e.which ? e.which : e.keyCode;

        if(KeyCode == 40)
            SelectRow(SelectedRow.nextSibling, SelectedRowIndex + 1);
        else if(KeyCode == 38)
            SelectRow(SelectedRow.previousSibling, SelectedRowIndex - 1);

        return false;
    }
    </script>

code behind code:

protected void GrdATDataView_RowCreated(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow && (e.Row.RowState == DataControlRowState.Normal || e.Row.RowState == DataControlRowState.Alternate))
    {
        e.Row.TabIndex = -1;
        e.Row.Attributes["onclick"] = string.Format("javascript:SelectRow(this, {0});", e.Row.RowIndex);
        e.Row.Attributes["onkeydown"] = "javascript:return SelectSibling(event);";
        e.Row.Attributes["onselectstart"] = "javascript:return false;";

    }
}