How can I call a Javascript function when a checkbox is checked when this checkbox is inside a gridview ?

protected void AlteraStatusExpiraSeteDias_Click(object sender, EventArgs e)

{

    for (int i = 0; i < grdImoveis2.Rows.Count; i++)

    {

        GridViewRow RowViewExpiraSeteDias = (GridViewRow)grdImoveis2.Rows[i];

        CheckBox chk = (CheckBox)grdImoveis2.Rows[i].FindControl(chkExpiraSeteDias);

        if (chk != null)

        {

            String codigo;

            if (chk.Checked)

            {

                codigo = (String)grdImoveis2.Rows[i].Cells[0].Text;                        

                ScriptManager.RegisterStartupScript(this.Page, this.GetType(), Registra, AlteraStatus(codigo);, false);

            }

        }

    }

}







<asp:GridView ID=grdImoveis2 CssClass=StyleGrid Width=100% runat=server AutoGenerateColumns=false DataSourceID=ds BorderWidth=0 GridLines=None>

    <AlternatingRowStyle BackColor=White CssClass=EstiloDalinhaAlternativaGrid  HorizontalAlign=Center/>

        <RowStyle CssClass=EstiloDalinhaGrid HorizontalAlign=Center />

        <HeaderStyle BackColor=#e2dcd2 CssClass=thGrid Height=20 />

    <Columns>

        <asp:BoundField HeaderText=Código DataField=Imovel_Id />

        <asp:BoundField HeaderText=Para DataField=TransacaoSigla />

        <asp:BoundField HeaderText=Valor DataField=ValorImovel DataFormatString={0:c} HtmlEncode=false />

        <asp:TemplateField HeaderText=Endereco>

            <ItemTemplate>

                <%# Eval(Logradouro) %>, <%# Eval(Numero) %>

            </ItemTemplate>

        </asp:TemplateField>

        <asp:BoundField HeaderText=Data Cadastro DataField=DataHora  DataFormatString={0:dd/MM/yyyy} HtmlEncode=false/>

        <asp:BoundField HeaderText=Data Expira DataField=DataExpira  DataFormatString={0:dd/MM/yyyy} HtmlEncode=false/>

        <asp:TemplateField HeaderText=Ação>

            <ItemTemplate>

                <asp:CheckBox ID=chkExpiraSeteDias runat=server onclick=alert('Foo') />

            </ItemTemplate>

        </asp:TemplateField>

    </Columns>

</asp:GridView>

Without the checkbox, when I put a image and put a link href to the javascript, it's works!, but with checkbox, no!