CountIFs with multiple criteria

Hi all,

I have a listed of donations that I need to count for a given month and year.
Which is all well and fine, except that I have do it for a particular segment as well (eg $50-75, $75-100, etc) This means there needs to be more than one criteria for my CountIF formula- greater than a value AND less than a value. I've looked through a series of other suggestions on the internet and tried to use the difference of two CountIFs to make this possible.
However, when I do this
=(COUNTIFS($F$2:$F$557898,"November",$G$2:$G$557898,"2008",$D$2:$D$557898,">75")-COUNTIFS($F$2:$F$557898,"November",$G$2:$G$557898,"2008",$D$2:$D$557898,"<=100"))
I get a negative value for what I am trying to count. I know this can't be right.
(eg: $ -1,481)

Where am I going wrong here? Can anyone please share any thoughts?