Whats wrong with how this is coded to were it is allowing anything to be inputted without recognizing errors?

$errors=0;
$error="The following errors occured while processing your form input.<ul>";
pt_register('POST','ip');
pt_register('POST','date');
pt_register('POST','Text');
pt_register('POST','URL');

$healthy = array("$", "%", "!", "<", ">");
$yummy   = array("", "", "", "", "");

$Text = str_replace($healthy, $yummy, $Text);
$URL = str_replace($healthy, $yummy, $URL);

if($URL=="http://www.")
{
die ("<center><br><br>Please enter a valid URL. Please go back and try again</center>");
}
else
{
// yay
}

if($Text=="My awesome site!")
{
die ("<center><br><br>Please enter something besides 'My awesome site!' for your URL text. Go back and try again.</center>");
}
else
{
// yay
}


if($Text=="My awesome site" || $URL=="http://www." ){
$errors=1;
$error.="<li>You forgot your text ad or URL to link the text ad to, please go back and try again.";
}

Yeah.. It's special... pt_register() function which is especially used to access the register global variables.. We obviously know that, all variables in php should begin with '$' sign... Here, they are replacing those special characters with null values at registered area... So only, this code shows the output without showning any errors....