SSI include virtual going to root without /

I'm running SSI on IIS 6 on a Win2003 server. Everything is setup according to MSDN specifications.

I need to include some files using the SSI include directive. Those files are in the same directory as the page that calls them using the include directives.

For example, my test page called test.shtml has inside it this include: <!-- #include virtual="file.inc" -->

The files test.shtm and file.inc are in the same directory which is not the root of the site.

The problem is that the include directive searches for file.inc as if it was in the root path of the website. In other words, it works as if I typed "/file.inc" instead of "file.inc" for the path.

I though that SSI virtual includes that use a path without the slash / search for the file in the same virtual folder as the caller.

Why is this happening? any ideas?

Many thanks!!