I am trying to get this formula to work in my macro, but it seems not to
accept the MROUND, I get a Sub or Function not defined error. I need the
MROUND so that I can get proper rounding results. The formula below is
working with times and without MROUND I sometimes get rounding errors. For
example:

15:21 - 15:00 returns .35 which should round to .4 but rounds to .3


TextBox10.Text = Format(Round(MROUND((CDate(TextBox9.Text) _
- CDate(TextBox8.Text)) * 24), 1), "#.0")