Issue with cascading calculation rules: bug or my fault?

[SteP[IT]]

I'm having issues with product calculation rules.

I need to implement those cascading rules:
1) apply a first discount to a Category named 'DISCOUNTED PRODUCTS'
2) apply a second (cascading) discount to a Customer Group named 'RESELLERS'

I have then implemented two calculation rules
a) one discount to be applied to the Category named 'DISCOUNTED PRODUCTS'
b) another discount to be applied to the Customer Group named 'RESELLERS'

I have then created a new product, and assigned it to the category  'DISCOUNTED PRODUCTS'.
Inside the product I have added two prices:
1) the first price is assigned to the default and to the anonimous groups [this one should be discounted applieng the a) rule]
2) the second price is assigned to the specific customer 'RESELLERS' to which I want to assign the further discount [this price should be discounted applying both the a) and the b) rule]
Both these two prices have the APPLY GENERIC RULES checked.

But the second price is NOT correctly discounted: the a) and b) discount rules are NOT applied in cascading, as expected. Only the first a) rule is applied...
Is there a way to get it working?

System is running on Joomla 2.5.9 - VM 2.0.20b

Waiting for your kindly reply/suggestions/help

[Milbo]

I have no clue, why the second price is not discounted. A configuration error is very likely.

[SteP[IT]]

I have double checked my config, and I'm not been able to find were the mistake is.
I attach here 2 screenshots from the backoffice, is there a way to give me a hint?
The first one is the list of discount rules, one aasigned to a category and one assigned to a group
The second one is the products a I see it after adding multiple prices assigned to each different group
As you can see, the list of rules applied to each price is the same, instead of being different as per rules creation.

[attachment cleanup by admin]

[SteP[IT]]

A further update to my report: after further checks, I have found that on frontend prices are correctly calculated! But in backend prices are wrongly displayed using ALL the rules you have set up, not applying any kind of relation they have with groups/products/dcategories. SO, if you assign a rule to a certain group, on frontend the price is correct, but in backend the same rule is applied also if price is assigned to another group. This is what makes me falling in asking for help In any case, the backend prices display is wrong: it should be corrected to be in accordance with calculation rules assignment.
Regards