If you are working with Excel 2010 on a Mac, when you export a .xls file into .csv,
you may end up having a semicolon separated file instead of .csv.
If that is the case, please go in your MAC to:
System Preferences > Language & Region > Advanced
You can choose whatever Format language and Currency you want.
However, you have to customise the "Numbers separators" for "Decimal"
use "." instead of "," as you can see in the the following picture.