disable gridview on check of checkbox

I have a requirement where I want to disable the gridview adding row functionality if User checks the checkbox which is outside the gridview, i want to disable the gridview row adding functionality.

Please suggest how to implement that.

Here is my code for gridview and checkbox.

<cc1:Grid ID="GrdPreEmp_Det" EnableTypeValidation="true" runat="server" Width="99%"
        AllowAddingRecords="true" AllowSorting="false" AutoGenerateColumns="false" FolderStyle="../../Styles/Grid/style_13"
        OnInsertCommand="GrdPreEmp_Det_InsertCommand" OnDeleteCommand="GrdPreEmp_Det_DeleteCommand"
        OnRebind="GrdPreEmp_Det_OnRebind">
        <ClientSideEvents OnBeforeClientDelete="GrdPreEmp_Det_OnClientDelete" OnBeforeClientInsert="GrdPreEmp_Det_nBeforeClientInsert" />
        <Columns>
            <cc1:Column AllowDelete="true" HeaderText="Delete" Width="8%">
            </cc1:Column>
            <cc1:Column ID="Column1" DataField="MKEY" HeaderText="Mkey" Visible="false" Width="0%"
                ReadOnly="true">
            </cc1:Column>
            <cc1:Column ID="Column2" DataField="SR_NO" HeaderText="Sr No" Visible="true" Width="10%"
                ReadOnly="true">
                <TemplateSettings TemplateId="GridTemplate1" />
            </cc1:Column>
            <cc1:Column ID="CompanyName" DataField="CompanyName" HeaderText="Company Name" Visible="true"
                Width="15%">
            </cc1:Column>
            <cc1:Column ID="Location" DataField="Location" HeaderText="Location" Visible="true"
                Width="12%">
            </cc1:Column>
            <cc1:Column ID="StartDate" DataField="StartDate" HeaderText="Start Date" Visible="true"
                Width="10%">
                <TemplateSettings EditTemplateId="TempPrevStartDate" />
            </cc1:Column>
            <cc1:Column ID="EndDate" DataField="EndDate" HeaderText="End Date" Visible="true"
                Width="10%">
                <TemplateSettings EditTemplateId="TempEndDate" />
            </cc1:Column>
            <cc1:Column ID="LastHeld" DataField="LastHeld" HeaderText="Last Held Designation"
                Visible="true" Width="15%">
            </cc1:Column>
            <cc1:Column ID="Reason" DataField="Reason" HeaderText="Reason Of Leaving" Visible="true"
                Width="15%">
            </cc1:Column>
        </Columns>
        <Templates>
            <cc1:GridTemplate runat="server" ID="GridTemplate1">
                <Template>
                    <b>
                        <%# (Container.RecordIndex + 1) %></b>
                </Template>
            </cc1:GridTemplate>
            <cc1:GridTemplate runat="server" ID="GridTemplate2" ControlID="txtDate" ControlPropertyName="value">
                <Template>
                    <table cellspacing="0" cellpadding="0" style="border-collapse: collapse;">
                        <tr>
                            <td valign="top">
                                <input type="text" id="txtDate1" class="ob_gEC" style="width: 85px;" />
                            </td>
                            <td valign="top">
                                <cc3:Calendar ID="caltxtDate1" runat="server" DatePickerMode="true" DateFormat="dd-MM-yyyy"
                                    TextBoxId="txtDate1" DatePickerImagePath="Images/icon2.gif" />
                            </td>
                        </tr>
                    </table>
                </Template>
            </cc1:GridTemplate>
            <cc1:GridTemplate runat="server" ControlID="txtPrevStartdate" ID="TempPrevStartDate">
                <Template>
                    <asp:TextBox ID="txtPrevStartdate" runat="server" ToolTip="Enter date in DD/MM/YYYY format"></asp:TextBox>
                </Template>
            </cc1:GridTemplate>
            <cc1:GridTemplate runat="server" ControlID="txtPrevEndDate" ID="TempEndDate">
                <Template>
                    <asp:TextBox ID="txtPrevEndDate" runat="server" ToolTip="Enter date in DD/MM/YYYY format"></asp:TextBox>
                </Template>
            </cc1:GridTemplate>
        </Templates>
        <AddEditDeleteSettings AddLinksPosition="Bottom" NewRecordPosition="Dynamic" />
    </cc1:Grid>

Also see the checkbox code:-

<asp:CheckBox ID="chkPrevData" runat="server" Text="Not Applicable as I am fresher"
        Font-Names="Arial, Helvetica, sans-serif;" Font-Size="10" />

I tried from the other links,but all were related to checkbox which is inside the gridview.

Have a look at the below screenshot.