PHP Help Needed!!!

[5vz-fe]

I am just playing with PHP with different webservers (IIS and Apache)
Running into one interesting probelm, I can't get html forms to pass variables into php script. Can anyone tell me if I did something wrong with the conf or ini files?

HTML:
<form method="POST" action="example18.php3">
<div align="left">

<font face="BankGothic Md BT">Admin password?</font>
<input type="password" name="pw" size="14"><input type="submit" value="Submit"></p>
</div></form>

PHP:
<?
$adminpass = "test123";
if ($pw == $adminpass)
{
print("Welcome to the administration area!");
}
else
{
print("Wrong password");
}
?>

When I run the html and submit it tells me undefined variable pw.

Anyone know why?