php - SoapFault - Function ("function_name") is not a valid method for this service - Magento 1.9

one text

i'm working on magento 1.9 and i have tried to create a custom soap api.

I followed the steps on this tutorial (and other ones) but i didn't manage to successfully call the functions, it always return => Function ("function_name") is not a valid method for this service.

Ps : when i retrieve the soap function i have never found the ones i created.

I tried to empty the cache, on php.ini i set

"soap.wsdl_cache_enabled = 0", 

When i instanciate SoapClient i do as followed =>

$client = new SoapClient('http://URL/index.php/api/v2_soap?wsdl=1', 
                            array('cache_wsdl' => WSDL_CACHE_NONE ));

So i assume it's not a cache issue

To call the function i use

$products = $client->vendorProductList($session);

And Here is my wsdl file

<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns:typens="urn:{{var wsdl.name}}"
            xmlns:xsd="http://www.w3.org/2001/XMLSchema"
            xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
            xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/"
            xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"
            name="{{var wsdl.name}}"
            targetNamespace="urn:{{var wsdl.name}}">
    <types>
        <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="urn:Magento">
            <import namespace="http://schemas.xmlsoap.org/soap/encoding/" schemaLocation="http://schemas.xmlsoap.org/soap/encoding/" />
            <complexType name="fieldInfo">
                <sequence>
                    <element name="entity_id" type="xsd:string"/>
                    <element name="name" type="xsd:string"/>
                </sequence>
            </complexType>
            <complexType name="fieldInfoArray">
                <complexContent>
                    <restriction base="soapenc:Array">
                        <attribute ref="soapenc:arrayType" wsdl:arrayType="typens:fieldInfo[]" />
                    </restriction>
                </complexContent>
            </complexType>
        </schema>
    </types>
    <message name="vendorProductListRequest">
        <part name="sessionId" type="xsd:string" />
    </message>
    <message name="vendorProductListResponse">
        <part name="products" type="typens:fieldInfoArray" />
    </message>
    <portType name="{{var wsdl.handler}}PortType">
        <operation name="vendorProductList">
            <documentation>List of products</documentation>
            <input message="typens:vendorProductListRequest" />
            <output message="typens:vendorProductListResponse" />
        </operation>
    </portType>
    <binding name="{{var wsdl.handler}}Binding" type="typens:{{var wsdl.handler}}PortType">
        <soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http" />
        <operation name="vendorProductList">
            <soap:operation soapAction="urn:{{var wsdl.handler}}Action" />
            <input>
                <soap:body namespace="urn:{{var wsdl.name}}" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </input>
            <output>
                <soap:body namespace="urn:{{var wsdl.name}}" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </output>
        </operation>
    </binding>
    <service name="{{var wsdl.name}}Service">
        <port name="{{var wsdl.handler}}Port" binding="typens:{{var wsdl.handler}}Binding">
            <soap:address location="{{var wsdl.url}}" />
        </port>
    </service>
</definitions>

PSS : I'm using php 5.6

CAN SOMEONE PLEASE HELP ME???

GREATLY APPRECIATE ANY HELP.