Free shipping problem

I have one problem, I hope we can understand each other.
shop has defined that delivery is free over 100 dollars

if you buy a product that costs 30 dollars and is marked with free shipping, and with it a product that costs, for example, 50 dollars, the site does not calculate free shipping.
what is the problem?

thanks

the product marked free should be free shipping no matter what promotion is applied.
but could possibly be this

Hi, tnx for answer, its marked for all products with free shipping.

Someone?
I have huge problem when customer pay with card online, he have calculated shipping to pay, after that i must sent him a cash.