OpenERP v7 Error on Report

I added a new report on stock module (into OpenERP v7), but the path to the rml file seems correct to me, when a click the 'print' button it says:

RML is not available at specified location or not enough data to print!

(None, None, None)

Should be an error in the path I specified on .py file, but I checked and re-checked and seems correct.

Here's my code:

import time
from openerp.report import report_sxw

class reporte_locacion(report_sxw.rml_parse):
    def __init__(self, cr, uid, name, context):
        super(reporte_locacion, self).__init__(cr, uid, name, context=context)
        self.localcontext.update({
             'time': time,
             'qty_total':self._qty_total
        })

def _qty_total(self, objects):
    total = 0.0
    uom = objects[0].product_uom.name
    for obj in objects:
        total += obj.product_qty
    return {'quantity':total,'uom':uom}

report_sxw.report_sxw(
    'report.reporte.locacion',
    'product.product',
    'addons/stock/report/reporte_locacion.rml',
    parser=reporte_locacion,
    header='internal'
)

I already have it on that location, could it be the stock_report.xml file?

Here's how I declare the report on it:

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>
        <report auto="False" id="reporte_locacion" model="product.product" name="reporte.locacion" string="Productos en almacen"/>
        <report auto="False" id="report_product_history" model="product.product" name="stock.product.history" string="Stock Level Forecast"/>
        <report id="report_picking_list" model="stock.picking" name="stock.picking.list" string="Picking Slip" rml="stock/report/picking.rml"/>
        <report id="report_picking_list_in" model="stock.picking.in" name="stock.picking.list.in" string="Receipt Slip" rml="stock/report/picking.rml"/>
        <report id="report_picking_list_out" model="stock.picking.out" name="stock.picking.list.out" string="Delivery Slip" rml="stock/report/picking.rml"/>
        <report id="report_move_labels" model="stock.move" name="stock.move.label" string="Item Labels" xml="stock/report/lot_move_label.xml" xsl="stock/report/lot_move_label.xsl"/>
        <report auto="False"  id="report_location_overview" model="stock.location" name="lot.stock.overview" string="Location Inventory Overview" rml="stock/report/lot_overview.rml"/>
        <report id="report_location_overview_all" model="stock.location" name="lot.stock.overview_all" string="Location Content" rml="stock/report/lot_overview_all.rml"/>
        <report id="report_stock_inventory_move" model="stock.inventory" name="stock.inventory.move" string="Stock Inventory" rml="stock/report/stock_inventory_move.rml"/>
    </data>
</openerp>

The first report on it being the one which is having an error, did I miss something there?

Should be fine since it's almost same declaration type as the other reports, and they all work fine though.

Any ideas?

Thanks in advance!

Declaration should be like this

<report id="reporte_locacion" 
        model="product.product" 
        name="reporte.locacion" 
        string="Productos en almacen" 
        rml="addons/stock/report/reporte_locacion.rml"/>