How to correctly place a range of numbers in COUNTIFS and SUMIFS formulas?

Hello everybody!

I am new here so I hope I won't accidentally breach any rules I tried searching but my problem is very difficult to look for because there are so many problems with different kinds of ranges.

This is my problem:

I want to place a formula =COUNTIFS which goes like this:

=COUNTIFS('Sheet1 '!$F$2:$F$445;C88; 'Sheet2'!$V$2:$V$445;"15<=>=30")

and I have a problem with this part: "15<=>=30"
This is supposed to count the records only if in a range $V$2:$V$445 there are numbers: (15, 16, 17, 18, ...., 29, 30). I thought that this "15<=>=30" should work just fine but it didn't count correctly so it looks like I've made a mistake. Could someone please help me? Excel doesn't see a problem with this part of the formula, there are no errors but when I search manually through my spreadsheet, I can see a record matching my criteria but COUNTIFS doesn't see this record.

How to correctly indicate in my formula that I am interested only in counting numbers that are "equal or greater than 15 AND equal or smaller than 30"?

The first part of my formula (not in bold) works just fine I also don't have a problem when I want to count, for example, something greater than 30. Or something smaller than 15. But I can't correctly place a range of numbers.

Thank you in advance for your help!

Regards,
Justyna