can't send variable

[moniphp]

I want to send a variable($priv) from frame login.php to main.php and this one send the variable to leer_datos.php. I can read the varible in main but in leer_datos I read nothing.

login.php:

header("Location: /main.php?nombre=$f_user&mrtg=$mrtg&ing=$ing&priv=$priv");

main.php:

if ($priv==3){
echo" {CASOS ABIERTOS,leer_casos.php?est=1&s=ABIERTOS&priv=$priv,_self}";

leer_datos.php:

echo " <FORM METHOD='POST' ACTION='leer_casos.php?var=1&est=$est&s=$s&priv=$priv'> ";

Thanks for the help.

[DigitalExpl0it]

try $_REQURST[]

echo "{CASOS ABIERTOS,leer_casos.php?est=1&s=ABIERTOS&priv=".$_REQUEST["priv"].",_self}";