UserForm help, assigning variable from option button selection

[colorado_adv]

I'm trying to utilize UserForm option buttons to get info from user. I want to assign the option button selection to a variable that can be used in both the Filename and in a cell in the Excel File as part of a string of text not exclusive to the variable.

See example UserForm code below. I want Month to be my variable. Assigned to my variable will be whatever the user selected.

I get "Compile error: Argument not optional"

If optionJanuary Then Month = "January"
If optionFebruary Then Month = "February"
If optionMarch Then Month = "March"
If optionApril Then Month = "April"
If optionMay Then Month = "May"
If optionJune Then Month = "June"
If optionJuly Then Month = "July"
If optionAugust Then Month = "August"
If optionSeptember Then Month = "September"
If optionOctober Then Month = "October"
If optionNovember Then Month = "November"
If optionDecember Then Month = "December"

Please help.