impossible to get fields

Hi,
I try to configure the module, between two servers on the same domain
drupal.mysite.com
moodle.mysite.com

I have install the drupal module, just create the field (firstname, lastname, country, town)
I have modified the setting.php with :
$cookie_domain = '.mysite.com';
I create a user (remote) and assign the role: Service-Authentication
nothing else concerning drupal.

on the mooddle side, the module is installed, and then I try to finish the configuration
He ask me for the Drupal Website URL : http://drupal.mysite.com
then he asks me to map the field but there's nothing in the form select?

If I try the endpoint url drupal.mysite.com/moodlesso /
Services Endpoint "moodlesso" has been setup successfully.

when I ask for the user informations, all the data seems ok :
drupal.mysite.com/moodlesso/user/2

<roles is_array="true">
<item>authenticated user</item>
<item>administrator</item>
<item>Service-Authentication</item>
</roles>
<field_firstname>
<und is_array="true">
<item>
<value>Christophe</value>
<format/>
<safe_value>Christophe</safe_value>
</item>
</und>
</field_firstname>
<field_lastname>
<und is_array="true">
<item>
<value>lili</value>
<format/>
<safe_value>lili</safe_value>
</item>
</und>
</field_lastname>
<field_city>
<und is_array="true">
<item>
<value>Monoblet</value>
<format/>
<safe_value>Monotu</safe_value>
</item>
</und>
</field_city>
<field_country/>
<field_services/>
<rdf_mapping>
<rdftype is_array="true">
<item>sioc:UserAccount</item>
</rdftype>
<name>
<predicates is_array="true">
<item>foaf:name</item>
</predicates>
</name>
<homepage>
<predicates is_array="true">
<item>foaf:page</item>
</predicates>
<type>rel</type>
</homepage>
</rdf_mapping>
<revision>1</revision>
</result>

Any ideas or debug tool I can use?