title: Unexpected behaviour of rewriterules in htaccess
body: <p>This is my htaccess file </p>
  
  <pre><code>RewriteEngine on 
  rewriterule ^([a-zA-Z0-9]+) /vixer.php?v=$1 [QSA] 
  </code></pre>
  
  <p>the main problem is that when I enter www.example.com/vix_25 it goes to 404 </p>
  
  <p>and when I enter another url /vix25 it works.. I really dont understand what is the diffrence and why 1st  doesnt work. </p>
  
  <p>Can you guys help me? thanks</p>