.htaccess file handles all virtual folder redirections, so the main reason for this may be the wrong code or absence of a .htaccess file, which should have been generated automatically by the script during installation.

Here is what to do:

1.                 Make sure that the .htaccess file is placed in the root folder of your site, not in the NP's folder.

2.                 Make sure that there are no physical folders on your site with the same names as your chosen virtual folders.

3. Create a new blank txt file and name it htaccess.txt. If you already have one, download it to from your site to your computer for editing and backup a copy.

4. Add the following code to your htaccess file:
 
#Foradwords
###############################
RewriteEngine On
RewriteBase /
RewriteRule ^virtual-incoming-folder/([a-zA-Z0-9]+)/$ /script-path/incoming.php?word_code=$1 [L,PT]
RewriteRule ^virtual-outgoing-folder/([a-zA-Z0-9]+)/(.+)$ /script-path/outgoing.php?word_code=$1&url=$2 [L,PT]
###############################

where you need to replace:
- virtual-incoming-folder
- virtual-outgoing-folder
- script-path
with the actual data of your NP installation. The rest of the code, please, keep intact, including spaces etc.

======== Example ========
If your
- virtual incoming folder is /in/
- virtual outgoing folder is /out/
- path to the script folder is /np/

then your correct htaccess code will be:

#Foradwords
###############################
RewriteEngine On
RewriteBase /
RewriteRule ^in/([a-zA-Z0-9]+)/$ /np/incoming.php?word_code=$1 [L,PT]
RewriteRule ^out/([a-zA-Z0-9]+)/(.+)$ /np/outgoing.php?word_code=$1&url=$2 [L,PT]
###############################
========================

5. Upload the new file to the root folder of your site, rename it to .htaccess if needed and try the redirection process again.