Pivot table Calculated field - Sumif(s) between two dates?

Question

I'm attempting to calculate periods of out of stock for a fleet of rental equipment that has been in service for the past few years. I'm having trouble creating a sumif calculated field that sums units by date if date is between start and finish. My data looks like this:

Calendar  |Start    |Finish    |Product   |Units
2015-12-06|2015-12-6|2015-12-6 |Snowshoes |2
2015-12-07|2015-12-6|2015-12-7 |Snowshoes |1

Calendar - is a helper column I've added. It's sequential dates from launch to the present Start - is the start Date of a rental booking Finish - end date of the rental booking Product - What's being rented Units - How many are rented for that booking

I'd like the pivot table to look like:

Date       | Snowshoes | Tent ... etc
2015-12-06 | 3         | 
2015-12-07 | 1         | 

I'm having a hard time setting up calculated field that will sum units if date is between start and finish, I keep getting formula errors.

Here's the formula I'm attempting to use to create a calculated field:

= sumifs( Units ,Start,">= Calendar" , Finish,"<= Calendar")

Is this even the best way to go about solving this problem? Is my formula the issue or is the entire approach flawed?

Adding screenshots:

Answer 1

From the data you have in the screenshots, this is what I came up.

The formula to use in column G:

=SUMIFS($E$2:$E$29,$A$2:$A$29,"<="&F2,$B$2:$B$29,">="&$F2)

The formula to use in column H (BTW, this is just for your reference. You can use either one of them):

=SUMPRODUCT(--($A$2:$A$29<=F2),--($B$2:$B$29>=F2),$E$2:$E$29)

From here, I created a Pivot Table like this:

Hopefully this can help you. But definitely let me know if I miss anything from your question.