Is this possible in Crystal Reports?

I am only capable of grouping my data by dates IF THE DATA EXIST IN THAT DATE.

But if there is no data in the field, how do I still show the date? (from the beginning to the end of the month)

I've stumbled across this article: Displaying All Missing Dates In a Range - A Custom Function Sample

But in the later parts of displaying the formula, no result is showing, although there are no errors in my function nor the formula already.
An administrator in a Crystal Report group in Facebook suggests that I convert the "Basic Syntax" given in this article to "Crystal Syntax".

I have changed the parameter from "date" (as the article suggested) to "datetime" because I am guessing it conflicts with my MS Access field's type.

Any help would be appreciated!

(Using Visual Studio 2010)
(Using OLEDB to populate reports)
(Using MS Access 2010 file as a database)