I need help, when i enable the entity_translation and entity_translation_upgrade modules the site breaks. It gives this message:

EntityMetadataWrapperException: Unknown data property commerce_line_items. in EntityStructureWrapper->getPropertyInfo() (line 339 of \sites\all\modules\entity\includes\entity.wrapper.inc).

I don't know if this is related with translation but i've already tested a couple of times and it happens the same. In this last one i even deleted all the products before enableing the modules. I really need this to work..
The only way i found to recover is to restore the database..