Attribute price is shown incorrectly

[igorlansky]

Hi,
I’m struggling too with setting up the quantity attribute to a product.
Here what happens:
I set up the price for 1.
Then I created attributes for 7, 14, 21, 28 , etc.
Each attribute contains a number of $ of increase.
I save it.
When seeing the product in the front shop I see that when I chose the attribute option, the price shown is not correct. The price shown is not exactly what I’ve set up as the price + increase. It’s less than increase.
Any comments?
Please, give me an idea what’s wrong.
Thank you for your help.
I’ll appreciate it !