SOAP 4 set_relationship not working - php

Question

After battling for getting more than 20 entries with get_entry_list, i'm now trying to use the SOAP API on SugarCRM 6.5 to set a relationship between two elements, created from a form on the user-land website.
The set_relationship method is described as following in the devs blog :
$response = set_relationship(session, module_name, module_id, link_field_name, related_ids, name_value_list, delete);
So here is the code which handles the request, assuming that another part of the code handles the security.
$values = array( 'id_frame' => $_POST['id_frame'],
'id_battery' => $_POST['id_battery'],
'reseller' => $_POST['reseller'],
'date_purchase' => $_POST['date_purchase'],
'products_versionning' => $_POST['product_purchased'],
'first_name' => $_POST['first_name'],
'last_name' => $_POST['name'],
'phone_home' => $_POST['phone'],
'email' => $_POST['email'],
'primary_address_street' => $_POST['address'],
'primary_address_street_2' => $_POST['address2'],
'primary_address_street_city' => $_POST['city'],
'primary_address_street_postalcode' => $_POST['zip'],
);
try{
$prod_register = $soapClient->set_entry(
$sessid,
'myco_product_register',
array( array('name' => 'id_frame', 'value' => $values['id_frame']),
array('name' => 'id_battery', 'value' => $values['id_battery']),
array('name' => 'date_purchase', 'value' => $values['date_purchase']),
array('name' => 'first_name', 'value' => $values['first_name']),
array('name' => 'last_name', 'value' => $values['last_name']),
array('name' => 'phone_home', 'value' => $values['phone_home']),
array('name' => 'email', 'value' => $values['email']),
array('name' => 'primary_address_street', 'value' => $values['primary_address_street']),
array('name' => 'primary_address_street_city', 'value' => $values['primary_address_street_city']),
array('name' => 'primary_address_street_postalcode','value' => $values['primary_address_street_postalcode']),
array('name' => 'description','value' => "Modèle : " . $values['products_versionning'] . "\nAcheté le " . $values['date_purchase'] . " à " . $values['reseller']),
)
);
$client = $soapClient->set_entry(
$sessid,
'Accounts',
array( array('name' => 'name', 'value' => $values['first_name'] . ' ' . $values['last_name']),
array('name' => 'billing_address_street', 'value' => $values['primary_address_street']),
array('name' => 'billing_address_city', 'value' => $values['primary_address_street_city']),
array('name' => 'billing_address_postalcode', 'value' => $values['primary_address_street_postalcode']),
)
);
$entry_id = $prod_register->id;
$relationship_parameters = array(
"module1" => "myco_product_register",
"module1_id" => array($entry_id),
"module2" => "myco_products_versionning",
"module2_id" => array($values['products_versionning'])
);
//Now i'm setting the relationships
$response = $soapClient->set_relationship($sessid, "myco_product_register", $entry_id,
'myco_products_versionning_id_c', $values['products_versionning'], array(), 0);
$response = $soapClient->set_relationship($sessid, "myco_product_register", $entry_id,
'myco_resellers_id_c', $values['reseller'], array(), 0);
Both set_entry requests work and return a working id, but no one of the relationships work ($responses contains a failed equal to 1). So that's not a connection problem or such.
Talking about the relationships, one guy from the devblog said that
there has to be a relationship between the two modules
there has to be at least one related field in the module which handle the relation, whose name you can find in the module's vardefs.php
and i have
A One-to-one relationship between the product_register module and both products_versionning and resellers
A related field in product_register for each related module.
What may i be missing ?

Answer 1

try checking the log file of SugarCRM, you should find some mistakes. I used this API to create a relationship between Contacts and Accounts, and working properly. On the logs might find the answer to the problem.
try {
$result = $this->soapClient->set_relationship($this->sessionId,
$accountModuleName, $accountId, $relationName, $contactsId);
$this->doEvent(self::EVENT_WS_OPERATION_CALL);
if ($result->created > 0 && $result->failed === 0) {
return true;
} else {
return false;
}