Im trying to make a simple survey in php

I have a set of radio buttons on a page called sja.php that sends its to sjamail.php page

the problem is that when i go to get

$answer = $_POST['ans'];

I can't seen to do anything like

echo "$answer";

but if i were to throw some logic at it

like

if ($answer == "ans1") {

    echo 'Correct';
}

else {

   echo 'Incorrect';
}    

IT will display correct or incorrect

so why is it i can't access the value of the radio button ans?