Get original URL for Link to a Document content type

Hello,

I'm having a SharePoint doc library with ItemAdded event receiver attached to it and "Link to a Document" content type enabled. My general question is:

How to get URL that the link points to?

I'll show you how I'm trying to achieve that:

SPWeb parentWeb = properties.Web;
if (properties.ListItem.ContentType.Name == LinkContentTypeName)
{
    object urlFieldValue = properties.AfterProperties["URL"];
    if (urlFieldValue != null && urlFieldValue.ToString() != String.Empty)
    {
    // continue
    }
}

But I always get null so I can't even get inside IF statement. I've tried to install ItemAdded event receiver as synchronous, but it didn't make a difference. I'd appreciate any ideas.

Regards

Tomasz