I have two date like this:

In case of negative time-error ,I want to subtract them reverse but it doesn’t work correctly.

>Solution :

It’s not an error, when you have a negative time or it’s to long, Excel show this information like this (############).

In that case it’s better use a normal condition like this:

=If(D5-D6<0; D6-D5; D5-D6)

In this case you have a correct result.