Counting true/false values form measure 'A', in measure 'B' on matrix visual - count

Question

I have a riport, in which I need to make a measure, which counts the 'true' values of another measure.
My partner's sales prices are calculated with a measure, which is then put into a matrix visual.
Column 'A' contains the partner name (as there are several) Column 'B' is the item name, 'C' is their sales price and 'D' is the price they should sell the product for.
Example_1 matrix visual with open hierarchy:
What I need, is a measure, that I can put into the matrix, which then calculates those items, that are not sold for the given price, so when I close the table hieararchy and I only see the partner's name, I should have the info of how many products they sell for lower than given sales price (making it easier to rank them)
What I'm having trouble with, is to count the 'true' values of a measure, with another measure.
It's important, that I cannot make a new colmn into the source tables. I must have a measure, which counts 'True' values of another, as their sales prices are also calculated.
Example_2 matrix visual with closed hieararchy with the needed result value:
The first two items from Example_1 were sold for a lower than given price. My first measure will determine this by doing a true/false logical test.
My second measure which gives back two, should calculate the 'true' values of the first measure.
Practically the measures should look like this:
Measure_1 = if([measure_salesprice] < sum('given_pricelist'[Price] , "Lower" , "Not lower")
--> this one works perfectly
Measure_2 = Calculate(DISTINCTCOUNTX('Sales table', 'Sales table[Item name]),[measure_lowerpricetruorfalse] = "Lower")
--> now, this doesn't
Is this possible somehow?
I've tried several DAX combinatains like:
Calculate --> DISTINCTCOUNT, COUNTROWS, COUNTA, COUNTAX, COUNTX( with filter)
Always the same true/false error.

Answer 1

Please be informed that There is no function in DAX called DISTINCTCOUNTX ----> It is DISTINCTCOUNT only as of 2 Nov 2022:
Regarding your question: Use this DAX Code As Measure:
You don't need to categorize them as Lower or not Lower if you don't need this info to use later.
YourMeasure =
VAR GroupLower = FILTER(
'Sales table', [Partner sales price] < [Given sales price])
RETURN
COUNTX(
GroupLower,[Item name])
If you try to test it on a matrix visual: