Select All Check box not Working.

'Sub checkall
    Public Sub MakeChecked(ByVal GridView As DataGridView, ByVal ColumnName As String)
        Dim UnCheckedItems = From Rows In GridView.Rows.Cast(Of DataGridViewRow)() Where CBool(Rows.Cells(ColumnName).Value) = False
        For Each item In UnCheckedItems
            item.Cells(ColumnName).Value = True
        Next
    End Sub
    'Sub uncheckall
    Public Sub MakeUnChecked(ByVal GridView As DataGridView, ByVal ColumnName As String)
        Dim UnCheckedItems = From Rows In GridView.Rows.Cast(Of DataGridViewRow)() Where CBool(Rows.Cells(ColumnName).Value) = True
        For Each item In UnCheckedItems
            item.Cells(ColumnName).Value = False
        Next
    End Sub

hey
 try this.
<pre lang="cs">function CheckAll(checkboxId, index) {
            var grid = document.getElementById('GridView1');

            if (grid.rows.length &gt; 0) {
                //loop starts from 1. rows[0] points to the header.
                for (i = 1; i &lt; grid.rows.length; i++) {
                    //get the reference of first column
                    if (index &gt; 0) {
                        cell = grid.rows[i].cells[index];
                        for (j = 0; j &lt; cell.childNodes.length; j++) {
                            //if childNode type is CheckBox
                            if (cell.childNodes[j].type == &quot;checkbox&quot;) {
                                //assign the status of the Select All checkbox to the cell checkbox within the grid
                                cell.childNodes[j].checked = checkboxId.checked;
                            }
                        }

                    }
                }
            }
        }</pre>

//Calling of function

<pre lang="xml">&lt;HeaderTemplate&gt;
                                                                                &lt;asp:CheckBox ID=&quot;chkHeader&quot; Text=&quot;Check&quot; runat=&quot;server&quot; ToolTip=&quot;Check All&quot; onclick=&quot;return CheckAll(chkHeader,1(columnNo));&quot; /&gt;
                                                                            &lt;/HeaderTemplate&gt;</pre>

This works for me
try and give replay
Best Luck