1st off, apologies to make the question migrate from elsewhere! It became an orphan at the earlier dwelling and hence is in the look out for a patron!
This place is a haven for all pundits and so here it is:

I read the article Create a Database-Driven Site In 30 Minutes! in WebMasterBase by Corbbmacc O'Connor and wanted to use ssi to call a text file to be icluded in one of my pages. I
used the following code snippet mentioned in the article:

<!--#set var="which" value="$QUERY_STRING_UNESCAPED" -->
<!--#if expr="$which != ''" -->
<!--#include virtual="/content/$which" -->
<!--#else -->
<!--#include virtual="/content/error.txt" -->
<!--#endif -->

It is working ok so far as to call an existing file (thru a query string), but it doesn't return
the "error.txt" file when a non existing file is called, which I intended to be done by these lines :
<!--#else -->
<!--#include virtual="/content/error.txt" -->
But what I get at such occasions is an error message that "[An error has occured while processing this directive]", but not the contents of error.txt file which I expect to be returned. I think the default error message is to be disabled and the customised "error.txt" must be included, which doesn't happen.
I have created and named the folders and files correctly.
Could you please offer me a solution?
Thank you
Regards.