ho questo form html

provavariabile.html
<html>

<head>
<meta http-equiv="Content-Language" content="it">
<meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
<title>LOG IN</title>
</head>

<body>
<form method="POST" action="provavariabile.php">
<p align="center"><font face="Arial" color="#009933" size="4">NOME :
<input type="text" name="variabile" size="20"></font></p>
<input type="submit" value="ENTRA" name="B1" style="font-family: Arial; font-weight: bold"><input type="reset" value="REIMPOSTA" name="B2" style="font-family: Arial; font-weight: bold"></font></p>


</body>

</html>


e passo la variabile variabile a provavariabile.php
provo a stamparla e mi dice che la variabile variabile non esiste

provavariabile.php

<?
echo"$$ciao";
?>