My "Day" function code keeps getting errors?

Thanks - I keep getting a "this object doesnt support this property or method" error message when I put....
Dim sigleday
Singleday = Day ....code into a textbox object on a form. Can you let me know what the problem is, and perhaps correct my code.

Regards - Paul

try this

Dim sigleday

Singleday = Day(date)
or
Singleday = Day(Now())