PHP session tracking - help required

[hrwebpro]

I'm totally new to PHP, so forgive my ignorance, but could anyone tell me where I'm going wrong here?

I'm trying to track visitors to our website who have been referred from other sites. I then want to pass on the affiliate's details when they leave the site.

The following script is at the top of the home page:

<?php session_start(); $_SESSION["affiliatecode"] = htmlentities(trim(@$_REQUEST["affiliatecode"])); ?>
<?php session_start(); $_SESSION["campaignID"] = htmlentities(trim(@$_REQUEST["campaignID"])); ?>
<?php session_start(); $_SESSION["sourceBusID"] = htmlentities(trim(@$_REQUEST["sourceBusID"])); ?>
<?php session_start(); $_SESSION["activityID"] = htmlentities(trim(@$_REQUEST["activityID"])); ?>

Then at the end of the link to leave the site I've got:

&affiliatecode=<?php echo @$_SESSION["affiliatecode"]."&campaignID".@$_SESSION["campaignID"]."&sourceID".@$_SESSION["sourceID"]."&activityID".@$_SESSION["activityID"];?>

The idea being that the variables "affilatecode", "campaignID", "sourceID" and "activityID" are passed to the external site.

At the moment, it just passes the affiliatecode and skips the rest.

Any ideas?

Thanks in advance

[Dan Grossman]

1) You only need to call session_start() once on the page, not before every access to $_SESSION

2) You are missing the = between the keys and values after every key except affiliatecode

You want "&campaignID=123", not "&campaignID123"

[guido2004]

Don't use @
Try this code:

<?php 
  session_start(); 
  $_SESSION['affiliatecode'] = htmlentities(trim($_REQUEST['affiliatecode']));
  $_SESSION['campaignID'] = htmlentities(trim($_REQUEST['campaignID'])); 
  $_SESSION['sourceBusID'] = htmlentities(trim($_REQUEST['sourceBusID']));
  $_SESSION['activityID'] = htmlentities(trim($_REQUEST['activityID']));
?>

[hrwebpro]

So would this be correct for the top of the page?

<?php session_start(); $_SESSION["affiliatecode"] = htmlentities(trim(@$_REQUEST["affiliatecode"]));
$_SESSION["campaignID"] = htmlentities(trim(@$_REQUEST["campaignID"]));
$_SESSION["sourceBusID"] = htmlentities(trim(@$_REQUEST["sourceBusID"]));
$_SESSION["activityID"] = htmlentities(trim(@$_REQUEST["activityID"])); ?>

[hrwebpro]

Thanks, Dan and guido, think I posted at the same time, but I'll try your code now.

[hrwebpro]

Ok, this is the code I'm using now, but it's still only passing the first variable:

<?php 
  session_start(); 
  $_SESSION["affiliatecode"] = htmlentities(trim(@$_REQUEST["affiliatecode"]));
  $_SESSION["campaignID"] = htmlentities(trim(@$_REQUEST["campaignID"])); 
  $_SESSION["sourceBusID"] = htmlentities(trim(@$_REQUEST["sourceBusID"]));
  $_SESSION["activityID"] = htmlentities(trim(@$_REQUEST["activityID"]));
?>

and then this code on the end of the link:

&affiliatecode=<?php echo @$_SESSION["affiliatecode"]."&ampcampaignID=".@$_SESSION["campaignID"]."&ampsourceBusID=".@$_SESSION["sourceBusID"]."&activityID=".@$_SESSION["activityID"];?>

I tried removing the @s from this, but it made no difference.