Select node based on sibling properties - HtmlAgilityPack - C#

I have a document in HTML that is set up as follows.

<ul class="beverageFacts">
<li>
    <span>Vintage</span> 
    <strong>2007&nbsp;</strong>
</li>
<li>
    <span>ABV</span> 
    <strong>13,0&nbsp;%</strong>
</li>
<li>
    <span>Sugar</span> 
    <strong>5&nbsp;gram/liter</strong>
</li>

I must parse the values of<strong> the associated tagsstring 's based on the value the<span> has, tag.

I have these things:

String vintage;
String sugar;
String abv;

I'm now cycling over each node's child to see whetherbeverageFacts validating the values to match them with the appropriate nodesstring . The following is the code I have so far to get the "Vintage"-value, however the outcome is alwaysnull .

HtmlNodeCollection childNodes = bevFactNode.ChildNodes;
foreach (HtmlNode subNode in childNodes)
{
    if (subNode.InnerText.TrimStart() == "Vintage")
        vintage = subNode.NextSibling.InnerText.Trim();
}

I think I chose the nodes incorrectly, but I can't seem to find out how to do it correctly and effectively.

Is there a simple method to do this?

Edit 2013-07-29

Using the following code, I have attempted to delete the whitespaces as advised by enricoariel in the comments.

        HtmlAgilityPack.HtmlDocument page = new HtmlWeb().Load("http://www.systembolaget.se/" + articleID);

        string cleanDoc = Regex.Replace(page.DocumentNode.OuterHtml, @"\s*(?<capture><(?<markUp>\w+)>.*<\/\k<markUp>>)\s*", "${capture}", RegexOptions.Singleline);

        HtmlDocument cleanPage = new HtmlDocument();
        cleanPage.LoadHtml(cleanDoc);

The outcome is still

 String vintage = null;