I’m afraid our software isn’t properly internationalized and it requires that the decimal separator be set to a period (.) — it won’t work when the decimal separator is set to a comma (,) — you’ll need to make this change in your OS settings.
This is an OS-level setting.
Mac OS X:
System Preferences | Languages & Region | Advanced | Number Separators | Decimal — change that to a period.
Windows:
Changing the decimal separator in Windows should be:
Start | Windows System | Control Panel | Change Date Time or Number Settings (left pane) | Additional Settings (button in lower right of dialog box) | Decimal symbol — change that to a period.
If that doesn’t help, let us know and we’ll help you puzzle it out.