Bridge VM / ERP

[ermes]

Hello everyone,
I wrote a bridge for a customer to interface virtuemart with his ERP. everything is nice and working except for the login phase. Let me explain: I take all the data via post request (username, password, product specifications etc ...) only when I go to call $productModel->store() tell me that I do not have the authorization, when in fact I am already logged in and I have also set the token in this way:
$token = vRequest::getFormToken();
vRequest::setVar ($token, 1);

Any idea to understand where I'm wrong? Where i can found the doc about it? Tnx.