Calculating hours worked overnight, (including 24 hours)

Hi All,

Can anyone solve this one for me?

I am trying to automate the hours worked on a site particularly overnight. For normal duties it is not a problem as I use the formula below, however I have some sites that work 24 hours a day and using this formula it returns zero?

=D19-C19+(C19>D19)

Where C19 is the start time and D19 is the finish time.

I appreciate any help you can provide.

Thank you,
Shaun.