I am in need of some help. I understand the IF statement in its basic form, but I have come upon the need for a more complex statement.

In the work sheet I have two columns that have dates in them, (B1 and D1). What I am trying to do is have column U1 show B1 date, if it has a date. If no date in column B1 then show D1 date in column U1, if no date inB1 or D1 then column U1 needs to show current date.

I have a second request with this, how do I get an error message to show if I知 trying to enter a date in column D1 when a date is already there? I知 using VBA here.
Thanks in advance for the help.
Book1.xlsm