WampServer

Hey!

I've recently installed the WAMP Server on my PC. Almost everything goes smooth, except one really disturbing problem, I hope you will be able to help me.

Look at this really simple code:

<?php

echo "<a href='check.php?op=write'>Write</a>";
?>

and then this:

<?php

switch($op){

case "write":
writefun();
break;

case "delete":
del();
break;

default:
echo "you-me";
break;
}

function writefun(){

echo "you";
}

function del(){

echo "delete-function";
}

?>

Of course you expect your PC to return "you". But mine goes to the default somehow and returns "you-me".
Now... I know there is no mistake here, I even checked this thing on a hosting server and it worked fine. I don't understand what the problem is...
Does somebody know what I can do with that?

Nobody knows?