Group by recipe and calculation

[DE_BYTEL]

I want to calculate the cost by multiplying a price with quantity of my equipment.

So I used a Group by recipe and here are the different steps that I take with the screens in attachment :

1. I select my field ''idnt_eqpm'' as Group key and I put "Compute count for each group'' for create a count field which I will name later

2. I create a field for calculate my cost 

3. I select my output : my group key field, my calculate field and my count field.

But I have this output error (screen) :

How can I resolve that and can I replace my group by recipe to do that ? 

Thank you.

[LouisDHulst]

Hi,

Im unsure what exactly you're trying to achieve here. If you want the total cost per group, could you not just sum the price column?

Is there any way you could show a sample of your input table? Thanks