Excel 2007 : Problem With #division/0!

First of all, i am quite new to excel (been using it for two weeks now), and i am creating a template, where i can put some data in and it calculates and so on. It's going really well except that in some situations keep running into the #division/0! error.

My formula looks like this:
=MIDDEL.HVISER('1'!H96:H160;'1'!F96:F160;">21";'1'!H96:H160;">0";'1'!F96:F160;"<6";'1'!F96:F160;">0")

Middel.hviser() is the danish equal to average.if.

as you can see i have written that the data has to be >0 in both columns. And thats why it puzzles me that #division/0 keeps returning.

sorry if this is a little hard to understand, as i am new to excel, my way around the right terms is a little hard.

Thanks
Kristoffer

I must admit im not quite sure what you mean, but i have no data which is below 0. I can attach my sheet if that would help?

A little more information on what i am trying to do.

The cells in the F column is the hours of the day, and H is the bloodpressure at the different times a day. i am trying to get the average of the hours of the night therefore it needs to be >21 and <6, as this is what the hours of the night in the project is set as.

DonkeyOte has a good point, but the question is now, how do i do it then?

With a little correction of some of the numbers (<6 instead of one of the >21) this worked perfectly, with the correct result, checked and double checked.
Thank you very much Donkey, it was very useful, i have to look it through a few times to exactley know how it works and what it does, but as i am new i have very much to learn. But it surely was a big help

No reason for the apology. You helped me a lot, the simplicity of it is astonishing.