Consultation des donnees oracle via PHP

Re-bonjour,
il m'affiche un message d'erreur:

Fatal error: Can't use function return value in write context in C:\wamp\www\ecran\base.php on line 275
la ligne 275 corresponde à : oci_result($schema, 2)=" ";
merci

merci de ton aide
voici le code en php

<?php
$conn = oci_connect("DBAR_ADMIN_BEN", "bfiguig1", "pdbar1_proradba1");

$stmt = oci_parse($conn, "SELECT LIBELLE, ID_SGBD, VERSION, ID_SERVEUR, MUTUALISE, PORT, CHARSET, TYPE_SAUVEGARDE, ID_DATABASE FROM DATABASE WHERE MUTUALISE = '".$mutualise."' and LIBELLE like '".$libelle."%' and VERSION like '".$version."%'");

oci_execute($stmt);

print '<table cellspacing="0" cellpadding="0" width="90%" border="1" align="center">';
print '<TR>';
print '<TD>BASE / INSTANCE</TD>';
print '<TD>SGBD</TD>';
print '<TD>VERSION</TD>';
print '<TD>SERVEUR</TD>';
print '<TD>MUTUALISE</TD>';
print '<TD>PORT</TD>';
print '<TD>CHARSET</TD>';
print '<TD>SAUVEGARDE</TD>';
print '<TD>SCHEMAS</TH>';
print '<TD>APPLICATIONS</TD>';
print '</TR>';


while (ocifetch($stmt))
{
$SGBD_value = oci_result($stmt, 2);
$SERVEUR_value = ociresult($stmt, 4);
$ID_DATABASE_value = ociresult($stmt, 9);

$ID_CHARSET_value = ociresult($stmt, 7);

$sgbd = oci_parse($conn, "SELECT LIBELLE FROM SGBD WHERE ID_SGBD = '".$SGBD_value."'");
oci_execute($sgbd);

$serveur = oci_parse($conn, "SELECT LIBELLE FROM SERVEUR WHERE ID_SERVEUR = '".$SERVEUR_value."'");
oci_execute($serveur);

$schema = oci_parse($conn, "SELECT s.ID_SCHEMA, s.LIBELLE FROM SCHEMA s, SCHEMA_DATABASE sc WHERE sc.ID_SCHEMA = s.ID_SCHEMA AND sc.ID_DATABASE = '".$ID_DATABASE_value."'");
oci_execute($schema);

print '<TR>';
print '<TD>' . ociresult($stmt, 1) . '</TD>';
while (ocifetch($sgbd))
{
print '<TD>' . ociresult($sgbd, 1) . '</TD>';
}
print '<TD>' . ociresult($stmt, 3) . '</TD>';

while (ocifetch($serveur))
{
print '<TD><a href="javascript:affiche_serveur()"><font color="#AF0635" style="FONT-WEIGHT: bold; FONT-SIZE: 11px"><span id="nom_serveur">'. ociresult($serveur, 1) .'</span></font></a></TD>';
}
print '<TD>' . ociresult($stmt, 5) . '</TD>';
print '<TD>' . ociresult($stmt, 6) . '</TD>';

if (!ociresult($stmt, 7))
{
print '<TD>  </TD>';
}
else
{
print '<TD>' . ociresult($stmt, 7) . '</TD>';
}

if (!ociresult($stmt, 8))
{
print '<TD>  </TD>';
}
else
{
print '<TD>' . ociresult($stmt, 8) . '</TD>';
}

while (ocifetch($schema))
{
$ID_SCHEMA_value = ociresult($schema, 1);

if (ociresult($schema, 2)=="")
{
print '<TD>  </TD>';
}
print '<TD><a href="javascript:affiche_schema()"><font color="#AF0635" style="FONT-WEIGHT: bold; FONT-SIZE: 11px"><span id="nom_serveur">'. ociresult($schema, 2) .'</span></font></a></TD>';
}

$application = oci_parse($conn, "SELECT a.LIBELLE FROM SCHEMA s, APPLICATION a WHERE s.ID_APPLICATION = a.ID_APPLICATION AND s.ID_SCHEMA = '".$ID_SCHEMA_value."'");
oci_execute($application, OCI_DEFAULT);

while (ocifetch($application))
{
if (ociresult($application, 1) != '')
{
print '<TD><a href="javascript:affiche_application()"><font color="#AF0635" style="FONT-WEIGHT: bold; FONT-SIZE: 11px"><span id="nom_serveur">'. ociresult($application, 1) .'</span></font></a></TD>';
}
else
{
print '<TD>  </TD>';
}
}
print '</TR>';
}
print '</table>';


oci_free_statement($stmt);
oci_close($conn);
?>

re-bonjour,
meme si je rajoute le else ca change rien
merci de ton aide