That is what I was saying earlier about your international region settings in MS windows. If you go to control panel, there is an applet for Regional and Language Options. It must be set to comma there in order to get the comma.
To get a period, you have two choices.
1. Go to that control panel setting and set the decimal separator to period.
2. In the format string, in your VI, make it %.;%.03f,%.03f,%.03f,%.06
That %.; (percent, period, semicolon) will override the Windows setting and force the decimal separator to period.