My guess is that you still have a broken rule in your config from earlier attempts to get this working. Perhaps you've attempted to do this redirect via a .htaccess file and httpd.conf and forgotten that a broken rule is still in effect in one of those files.
Also, how are you testing this? Do you have a UNIX like system you can work with? If so I would recommend hand-crafting the request and using the nc command to issue it. That gives you maximum control and makes it easy to see exactly what the web server is returning. For example, I created a file name "g.req" with the following contents then ran ```nc localhost 80 < g.req``` from a terminal window. Note that the last line of the file is an empty line.
```
GET /hello.php?action="" HTTP/1.1
User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0