HTMLAgilityPack parse table within another table cell

I have the following table:

<table>
    <tr><th>header1</th><th>header2</th><th>header3</th></tr>
    <tr><td>value01</td><td>value02</td><td>value03</td></tr>
    <tr><td>value11</td><td>value12</td><td>value13</td></tr>
    <tr>
        <td colspan="3">
            <table>
                <tr><td>subvalue01</td><td>subvalue02</td></tr>
            </table>
        </td>
    </tr>
</table>

I'm using this code to save the main table cell values into separate ArrayList and subtable cell values in another ArrayList. But my ArrayList for subtable cell values is saving the entire values including table and subtable:

foreach (HtmlNode table in hdoc.DocumentNode.SelectNodes("//table"))
{
    ///This is the table.
    foreach (HtmlNode row in table.SelectNodes("tr").Skip(1))
    {
        ///This is the row.
        foreach (HtmlNode cell in row.SelectNodes("th|td")) 
            ///can also use "th|td", but right now we ONLY need td
        {
            //This is the cell.
            if (cell.InnerHtml.Contains("<table>"))
            {
                foreach (HtmlNode subtable in cell.SelectNodes("//table"))
                {
                    foreach (HtmlNode subrow in subtable.SelectNodes("tr").Skip(1))
                    {
                        foreach (HtmlNode subcell in subrow.SelectNodes("th|td"))
                        {
                            arrSubList.Add(subcell.InnerText);
                        }
                    }
                }
            }
            else
            {
                arrList.Add(cell.InnerText);
            }
        }
    }
}

What is wrong with my code?