Resolver not working when transforming

[Gustaf]

I'd like to see if someone found a natural explanation to this. I have
this method for transforming docs:

/**
* Transforms an XmlDocument object with an XSL file, and returns
* another XmlDocument object. If something bad happens, null is
* returned instead.
*/
private XmlDocument Transform (string xml, string xsl)
{
try
{
XmlDocument xmlDocIn = new XmlDocument();
xmlDocIn.Load(xml);
XslTransform transformer = new XslTransform();
transformer.Load(xsl);
XmlDocument xmlDocOut = new XmlDocument();
xmlDocOut.Load(transformer.Transform(xmlDocIn, null, new
XmlUrlResolver()));
return xmlDocOut;
}
catch
{
return null;
}
}

Some stylesheets are calling other documents, so I need the resolver to
work. And it works fine when I run this as a standalone app:

using System;
using System.Xml;
using System.Xml.XPath;
using System.Xml.Xsl;

namespace XslTest3
{
class Test
{
[STAThread]
static void Main(string[] args)
{
XmlDocument xmlDocResult = Transform(args[0], args[1]);
xmlDocResult.Save(args[2]);
}

private static XmlDocument Transform (string xml, string xsl)
{
try
{
XmlDocument xmlDocIn = new XmlDocument();
xmlDocIn.Load(xml);
XslTransform transformer = new XslTransform();
transformer.Load(xsl);
XmlDocument xmlDocOut = new XmlDocument();
xmlDocOut.Load(transformer.Transform(xmlDocIn, null,
new XmlUrlResolver()));
return xmlDocOut;
}
catch
{
return null;
}
}
}
}

But when I paste *exactly* the same method (just removing "static") into
my main app, the resolver stops working! The transformation works, but
no data from the documents called from stylesheets come out.

Gustaf