I'm trying to modify a module's behaviour using another module, but I keep getting the same error message.

Traceback (most recent call last):
File "/home/carlos/dbTest/codigo/OCB/openerp/http.py", line 537, in _handle_exception
return super(JsonRequest, self)._handle_exception(exception)
File "/home/carlos/dbTest/codigo/OCB/openerp/http.py", line 574, in dispatch
result = self._call_function(**self.params)
File "/home/carlos/dbTest/codigo/OCB/openerp/http.py", line 310, in _call_function
return checked_call(self.db, *args, **kwargs)
File "/home/carlos/dbTest/codigo/OCB/openerp/service/model.py", line 118, in wrapper
return f(dbname, *args, **kwargs)
File "/home/carlos/dbTest/codigo/OCB/openerp/http.py", line 307, in checked_call
return self.endpoint(*a, **kw)
File "/home/carlos/dbTest/codigo/OCB/openerp/http.py", line 803, in __call__
return self.method(*args, **kw)
File "/home/carlos/dbTest/codigo/OCB/openerp/http.py", line 403, in response_wrap
response = f(*args, **kw)
File "/home/carlos/dbTest/codigo/OCB/addons/web/controllers/main.py", line 944, in call_kw
return self._call_kw(model, method, args, kwargs)
File "/home/carlos/dbTest/codigo/OCB/addons/web/controllers/main.py", line 936, in _call_kw
return getattr(request.registry.get(model), method)(request.cr, request.uid, *args, **kwargs)
File "/home/carlos/dbTest/codigo/OCB/openerp/api.py", line 268, in wrapper
return old_api(self, *args, **kwargs)
File "/home/carlos/dbTest/codigo/OCB/addons/mail/mail_thread.py", line 348, in fields_view_get
res = super(mail_thread, self).fields_view_get(cr, uid, view_id=view_id, view_type=view_type, context=context, toolbar=toolbar, submenu=submenu)
File "/home/carlos/dbTest/codigo/OCB/openerp/api.py", line 268, in wrapper
return old_api(self, *args, **kwargs)
File "/home/carlos/dbTest/codigo/OCB/openerp/models.py", line 1545, in fields_view_get
xarch, xfields = View.postprocess_and_fields(cr, uid, self._name, etree.fromstring(result['arch']), view_id, context=ctx)
File "/home/carlos/dbTest/codigo/OCB/openerp/api.py", line 268, in wrapper
return old_api(self, *args, **kwargs)
File "/home/carlos/dbTest/codigo/OCB/openerp/addons/base/ir/ir_ui_view.py", line 837, in postprocess_and_fields
self.raise_view_error(cr, user, message, view_id, context)
File "/home/carlos/dbTest/codigo/OCB/openerp/api.py", line 268, in wrapper
return old_api(self, *args, **kwargs)
File "/home/carlos/dbTest/codigo/OCB/openerp/addons/base/ir/ir_ui_view.py", line 360, in raise_view_error
raise AttributeError(message)
AttributeError: Field `code` does not exist
Error context:
View `CRM - Claims Tree`
[view_id: 1015, xml_id: crm_claim.crm_case_claims_tree_view, model: crm.claim, parent_id: n/a]

This is the module I'm trying to modify. This module modifies the behaviour of crm.claim, and it works fine

        from openerp import models, fields, api
    class CrmClaim(models.Model):
        _name = "crm.claim.code"
        _inherit = "crm.claim"
        code = fields.Char(
            string='Claim Number', required=True, default="/", readonly=True)
        _sql_constraints = [
            ('crm_claim_unique_code', 'UNIQUE (code)',
             'The code must be unique!'),
        ]
        @api.model
        def create(self, vals):
            if vals.get('code', '/') == '/':
                vals['code'] = self.env['ir.sequence'].get('crm.claim')
                #vals['stage_id'] = '1' #Set stage to "New" automatically
            return super(CrmClaim, self).create(vals)

This is the previou's module's XML view

<?xml version="1.0" encoding="UTF-8"?>
<openerp>
<data>
<record model="ir.ui.view" id="crm_claim_add_seq_form_view_inh">
<field name="name">crm.claim.add.seq.form.view.inh</field>
<field name="model">crm.claim</field>
<field name="inherit_id" ref="crm_claim.crm_case_claims_form_view" />
<field name="arch" type="xml">
<field name="name" position="before">
<field name="code" />
</field>
</field>
</record>
<record model="ir.ui.view" id="crm_claim_add_seq_tree_view_inh">
<field name="name">crm.claim.add.seq.tree.view.inh</field>
<field name="model">crm.claim</field>
<field name="inherit_id" ref="crm_claim.crm_case_claims_tree_view" />
<field name="arch" type="xml">
<field name="name" position="before">
<field name="code" />
</field>
</field>
</record>
<record model="ir.ui.view" id="view_crm_case_claims_filter_inh_claimseq">
<field name="name">view.crm.case.claims.filter.inh.claimseq</field>
<field name="model">crm.claim</field>
<field name="inherit_id" ref="crm_claim.view_crm_case_claims_filter" />
<field name="arch" type="xml">
<field name="name" position="attributes">
<attribute name="filter_domain">['|', ('name', 'ilike', self), ('code', 'ilike', self)]</attribute>
</field>
</field>
</record>
</data>
</openerp>

This is my module, I'm just trying to force the stage set to 1 (New) after a claim is created.

        from openerp import models, fields, api
    class CrmClaim(models.Model):
        _name = "crm.claim.code"
        _inherit = "crm.claim"
        code = fields.Char(
            string='Claim Number', required=True, default="/", readonly=True)
        _sql_constraints = [
            ('crm_claim_unique_code', 'UNIQUE (code)',
             'The code must be unique!'),
        ]
        @api.model
        def create(self, vals):
            if vals.get('code', '/') == '/':
                vals['code'] = self.env['ir.sequence'].get('crm.claim')
                #vals['stage_id'] = '1' #Set stage to "New" automatically
            return super(CrmClaim, self).create(vals)

And this is my directory's structure

odoo

    |[...]
    |Upgrade        (This is mine)
    |  |crm_claim_create
    |       |crmClaimCreate.py
    |
    |crm            (This is the one I'm trying to modify)
    |  |crm_claim_code
    |       |models
    |       |  |crm_claim.py
    |       |views
    |          |crm_claim_view.xml
    |OCB            (Odoo's base one)
       |addons
            |crm_claim
               |crm_claim.py 

Any idea what's happening?

Thank you