Extract attribute's value in lxml with XPath
===

I have the HTML:

    <table cellspacing="0" cellpadding="0" border="0">
    <tbody><tr>
    <td align="left" valign="top" style="padding: 0 10px 0 60px;">
    <img src="/files/39.jpg" width="64" height="64">
    </td>
    <td align="left" valign="middle"><h1>30 Rock / 30 потрясений</h1>
    </td>
    </tr>
    </tbody>
    </table>

I need to get the code, which extacts src-value from img tag - to do it I use python and lxml.
So - I need the correct from of Xpath (current version I obtained from Chrome)

    import lxml.html
    import urllib

    # make HTTP request to site
    page = urllib.urlopen("http://my.url.com")
    # read the downloaded page
    doc = lxml.html.document_fromstring(page.read())

    txt1 = doc.xpath('/html/body/table[2]/tbody/tr/td[1]/img')

After print txt1 I get the empty list only []. How to correct this sutuation ? 

 