I dont get this!

[Peter Sundling]

Problem solved.
I got some answers from you and most of you wrote that the code snippet
worked
for you, but it didn't for me.

Erik Max Francis told me that the problem could be elsewhere in the
code. 
Emile van Sebille gave me the idea that maybe one or more of the
variables could be strings. And there was the problem.
I loaded some data for the low[] and high[] variable from a file and
forgot
to convert the strings to integers. I feel like the dumbest programmer
in the world.

Thank you all for your help.

Regards,
Peter Sundling