Excel Vba Calculating Days Between Two Dates

Calculating Days Between Date In Cell And Today 

            On userform ,days can be calculated until date in cell from today's date. Related codes :

"...

TextBox15.Value = DateDiff("d", Date, Cells(ActiveCell.Row, 1).Value)
If Not IsDate(Cells(ActiveCell.Row, 1)) Then
TextBox15.Value = "Incorrect Value !"
End If
...
"