PHP表单邮件 - 内爆函数返回错误

Question

My form is working but I am seeing the following error in my scripts.log file

PHP Warning: implode() [function.implode]: Invalid arguments passed

Here is my HTML:

        <td><select name="additional_events[]" size="8" multiple="multiple" class="formFields">
 <option selected></option><?php echo $drop_down_list;?> 
    </select></td>

Here is the PHP:

$additional_events = trim(stripslashes(implode("  ///  ", $_POST['additional_events']))); 

Any suggestions would be helpful.