Help with htaccess

Ok, for the most part I have got this sorted. But I need a little help if that is ok?

Here is my htaccess:

ErrorDocument 404 /404.html
RewriteEngine On
RewriteRule ^rss.xml$ index.php?page=rss
RewriteRule ^([a-z0-9+])/([a-z0-9+])_([a-z0-9+])/$ index.php?page=details&entryid=15
RewriteRule ^([A-Za-z0-9]+)/$ index.php?page=listcategory&category=$1

Code (markup):

Now line 1 works
line 2 works
line 3 works
line 4 DOES NOT WORK
line 5 works

Can someone explain what I am doing wrong with line 4?
Line 4 is
RewriteRule ^([a-z0-9+])/([a-z0-9+])_([a-z0-9+])/$ index.php?page=details&entryid=15

And should be working from a url of
/ebooks/10_product_name_in_url_here/

If anyone can help I would be most thankful.

Kind Regards,
David

 

RewriteRule ^([a-z0-9+])/([a-z0-9+])_([a-z0-9+])/$ index.php?page=details&entryid=15

Im just curious, why did you put ID 15 after entryID variable?
It seems that you have only pass 2 variables, so you can use this

//Using 3 (..) means you are passing 3 variables, but in your case you only
//have 2.
RewriteRule ^([a-zA-Z0-9]+)/(.*?)\/$ index.php?page=details&entryid=15

PHP:

Or just in case the variable you are passing is after the "_" underscore and doesn't need the rest, then you can use either one. Depends which one suit your situation. But Im still confused, why did you use static variable value instead of dynamic, then what is the use of rewriting the URL?

 
//try this
RewriteRule ^([a-zA-Z0-9]+)/[^>]+_(.*)\/$ index.php?page=$1&entryid=$2 [L]

//or this
RewriteRule ^[^>]+/[^>]+_(.*)\/$ index.php?page=$details&entryid=$1 [L]

PHP: