Export Outlook Calendar to datatable

Hello everyone, I am using the Export Outlook Calendar to Datatable but I am noticing something strange and I would like to know if anyone had the same issue.

<From> : Date.ParseExact(fromDate,"dd,MM,yyyy",System.Globalization.CultureInfo.InvariantCulture)
<Till> : Date.ParseExact(tillDate,"MM,dd,yyyy",system.Globalization.CultureInfo.InvariantCulture)

This is what I use normally but I am noticing that every begging of the week it fails to retrieve the information and I need to change the Date.ParseExact(fromDate,"dd,MM,yyyy",System.Globalization.CultureInfo.InvariantCulture) into Date.ParseExact(fromDate,"MM,dd,yyyy",System.Globalization.CultureInfo.InvariantCulture) because otherwise it says "The DateTime represented by the string is not supported in calendar System.Globalization.GregorianCalendar."
And than middle of the week I have to change the from ddMMyyyy to MMddyyyy