calculating date/time with blank cells

[Guest]

A B C D
03/31/07 17 40 3/31/07 17:40
04/01/07 14 45 4/1/07 14:45
04/01/07 13 45 4/1/07 13:45
1/0/00 0:00
04/01/07 21 40 4/1/07 21:40
1/0/00 0:00
1/0/00 0:00

Can anyone tell me how I can just get a blank cell in column D when there is
no data to calculate . I'm using this formula:

=A2+B2/24+C2/(24*60)

Thank you in advance for your time
Deb

 

[Guest]

=IF(A1="","",A1+TIME(B1,C1,0))

Format cells as: m/d/yyyy h:mm

 

[Guest]

Thank you so much!

=IF(A1="","",A1+TIME(B1,C1,0))

Format cells as: m/d/yyyy h:mm