Purchase Order Lines With Discounts (purchase_discount) - is not working

Purchase Order Lines With Discounts (purchase_discount) - is not working

My environment:

Ubuntu 12.04
OpenERP 7.0
Chrome

relevant addons: account_anglo_saxon

relevant configuration:
    Inventory Valuation: Real Time (automated)
    Costing Method: Average Price
    Default invoicing control method: Pre-generate draf invoices based on purchase orders
    Purchase Order: Compute product cost price based on average cost
    Language: Spanish (CO) - Decimal Separator (,) - Thousands Separator (.)

Bug:

In the form "Order Lines" with discount (10%, or whatever) the field "Unit Price" is not updated, still equals to "Base Unit Price".

The order line stays red color.

If in discount field put 0.10 then is generated a infinite loop.