The price on sale order is not working when I change the UOM.

I have the following configuration on sale:

Unit of measure: Some products may be sold/purchased in different units of measure (Advanced)

Sale Price: Advaced pricing based on formulas (discounts, margins, rounding)

Discount: Allow discounts on sale order lines

I have kg as the Reference UOM for weight and "10 kg" as:

Category: Weight

Type: Bigger...

Bigger ratio: 10.0

I have the following Product:

Sale price: 100

Unit of measure: kg

Purchase UOM: kg

My pricelist:

Discount policy: Show public price & discount to the customer

Items:

All products - 10% discount

My sale order with default UOM it's OK:

UOM: kg, Unit price:100, discount %:10, subtotal: 90

But my sale order when I change my UOM:

UOM: 10 kg, Unit price:90, discount %:0, subtotal: 90

There are two problems:

1) It doesn't change the unit price, it should be 100*10 (for UOM 10kg)

2) The discount gets included in the unit price, the unit price is 90 and should be 100*10 and the discount is 0 and should by 10.

Is there a configuration that I'm doing wrong or is it a bug??

Thanks