Hello there, this is my first post here, and I've just started javascript. My problem is that I get an undefined error on this page after i write the result and click on the "Click Here to vote" button.

Here's the page : http://85.204.99.55/top5/index.php?a=in&u=crimes

(Hope this won't be considered advertising)


My script source is :


Code:
            
    <script type="text/javascript">
    var a = Math.ceil(Math.random() * 20);
    var b = Math.ceil(Math.random() * 20);       
    var c = a + b
    function DrawBotBoot()
    {
        document.write("What is "+ a + " + " + b +"? ");
        document.write("<input id='BotBootInput' type='text' maxlength='2' size='2'/>");

    }    
    function ValidBotBoot(){
        var d = document.getElementById('BotBootInput').value;
		
        if (d == c){   
		        window.location = "{$list_url}/index.php?a=in&amp;u={$username}&amp;sid={$sid}";
				
     }
	 else
        return false;
		
        
    }
    </script>

    
    
    
</head>
<body>

Are you human?<br />

<script type="text/javascript">DrawBotBoot()</script>
<input id="Button1" type="button" value="Click Here to Vote" onclick="alert(ValidBotBoot());"/>
The original code :

Code:
    <script type="text/javascript">
    var a = Math.ceil(Math.random() * 10);
    var b = Math.ceil(Math.random() * 10);       
    var c = a + b
    function DrawBotBoot()
    {
        document.write("What is "+ a + " + " + b +"? ");
        document.write("<input id='BotBootInput' type='text' maxlength='2' size='2'/>");
    }    
    function ValidBotBoot(){
        var d = document.getElementById('BotBootInput').value;
        if (d == c) return true;        
        return false;
        
    }
    </script>

    
    
    
</head>
<body>

Are you human?<br />

<script type="text/javascript">DrawBotBoot()</script>
<input id="Button1" type="button" value="Check" onclick="alert(ValidBotBoot());"/>

What am i missing? What did i do wrong?

Thank you in advance and have a nice day !