form submit button returns null if value contains non-latin words <p>this is my HTML:</p> <pre><code> &lt;?php echo form_open(base_url().'admin'); ?&gt; &lt;div class="row username"&gt; &lt;span class="icon"&gt;&lt;/span&gt; &lt;input type="text" value="" name="username" placeholder="Όνομα" /&gt; &lt;/div&gt; &lt;div class="row password"&gt; &lt;span class="icon"&gt;&lt;/span&gt; &lt;input type="password" value="" name="password" placeholder="Κωδικος Πρόσβασης" /&gt; &lt;/div&gt; &lt;div class="row button"&gt; &lt;input type="submit" value="Σύνδεση" name="submit" /&gt; &lt;/div&gt; &lt;?php echo form_close(); ?&gt; </code></pre> <p>so the button has as value "Σύνδεση" and when i click the submit button it returns nothing(null string)...</p> <p>if i replace it with a text like "Sign in" it will work...</p> <p>why it wont allow me to use non-latin characters?</p>