PHP LDAP queries bring back different results every time - php

Question

I am using PHP4 (cannot upgrade) to query around 2,000 accounts but it's bringing back different results each time I refresh the page. If I shrink the number down to around 800 the results are still different each time, if I move down to around a dozen then I get the same results each time. Please can anyone advise?
<?php
set_time_limit(0);
$user = "CN=Account Name,OU=Users,OU=Helpdesk,OU=Group IT,DC=domain,DC=co,DC=uk";
$psw = "PasswordHere";
$csv = file('AD-Managers.csv');
foreach ($csv as $line){
$names = explode(",",$line);//explode by commas
$managerExists = "0";
$managerUPN = $names[4];
$managerSearch = "userprincipalname=".$managerUPN;
$search = "userprincipalname=".$userUPN;
$server = "jpr-ads-01s.jpress.co.uk";
$dn = "DC=domain,DC=co,DC=uk";
$ds=ldap_connect($server) or die("Could not connect to {$ldaphost}");
ldap_set_option($ds, LDAP_OPT_PROTOCOL_VERSION,3);
ldap_set_option($ds, LDAP_OPT_REFERRALS,0);
if($r=ldap_bind($ds, $user , $psw)){ //using bind as I will be updating accounts once I get it working
$sr=ldap_search($ds, $dn, $managerSearch);
$data = ldap_get_entries($ds, $sr);
//array shift as the first result in the array is NULL
$daa = array_shift($data);
foreach($data as $userData){
if (strpos($userData["dn"], 'Google Apps') == false){//make sure it's not a contact
$managersName = $userData["distinguishedname"][0];
$managerExists = "1";
break; //stop the loop if the user is found
}
}
}
ldap_close($ds);
if($managerExists == "1"){
echo "manager: ".$managerUPN;
echo "<br />";
}
else{
echo "manager not found: ".$managerUPN;
echo "<br />";
}
}
?>
sample of CSV:
1234567,John Smith,JOHN SMITH,john.smith#domain.co.uk,johns.manager#domain.co.uk,ABC1234,1,,,,,,,,,,,,
8901234,Jane Doe,JANE DOE,jane.doe#domain.co.uk,janes.manager#domain.co.uk,DEF7890,2,,,,,,,,,,,,
Sample result 1:
manager not found: johns.manager#domain.co.uk
manager not found: janes.manager#domain.co.uk
But I could refresh the page instantly and get:
manager: johns.manager#domain.co.uk
manager: janes.manager#domain.co.uk