XAMPP问题：php_value include_path无效

I can't get php_value include_path to work with XAMPP. It seems as though it should be an easy to solve problem, but have been searching and trying for hours.

Modifying the root in Apache's/XAMPP's httpd.cfg works like a charm, but attempting to do the same in the .htaccess file simply doesn't. Here's my full .htaccess file (everything works except this aspect):

Options +FollowSymLinks -MultiViews
rewriteEngine on
RewriteBase /

## Hide .php extension by external redirection:
RewriteCond %{THE_REQUEST} ^[A-Z]{3,}\s([^.]+)\.php [NC]
RewriteRule ^ %1 [R,NC]

## Internally redirect to .php extension:
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^ %{REQUEST_URI}.php

RewriteCond %{REQUEST_URI} !^/products/.*$

## Redirect to index when page is missing.
ErrorDocument 404 http://www.xxxxx.xxx

php_value include_path ".:D:/Applications/XAMPP/htdocs/project1"

I've tried endless variations:

".:D:\Applications\XAMPP\htdocs\project1"

.:D:/Applications/XAMPP/htdocs/project1

".:/project1"

And all variations of this. I simply can't figure it out. Anyone any suggestions?

In windows you use a ; and not a : as a seperator in path statements, so try

php_value include_path ".;D:/Applications/XAMPP/htdocs/project1"