how solve this error message in my website?

<script runat="server">

    protected void Page_Load(object sender, EventArgs e)
    {
        fillpage();
    }
    private void fillpage()
    {
        ArrayList comuterlist = connectionclass.getcomputertype(!IsPostBack ? "%" : DropDownList1.SelectedValue);
        StringBuilder sb = new StringBuilder();
        foreach (Cpmuter computer in comuterlist)
        {
            sb.Append(   //this error
                string.Format(
              @"<table class='computertable'>
<tr>

         <th rowspan='6' width='150px'><img runat='Server' src='{6}'></th>
         <th width='50px'>Name:</th>
         <td>{0}</td>
</tr>

<tr>

         <th>Type:</th>
         <td>{1}</td>
</tr>
<tr>

         <th>Processor:</th>
         <td>{2}</td>
</tr>
<tr>

         <th>Ram:</th>
         <td>{3}</td>
</tr>
<tr>

         <th>Price:</th>
         <td>{4}</td>
</tr>

</table>",
         computer.name, computer.price, computer.processor, computer.ram, computer.type, computer.image));
            lblout.Text = sb.ToString();
        }
    }

    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        fillpage();
    }
</script>