Formula to calculate working hours between two dates not working correctly?

Pl see the attached file with formula in "d" column

Thanks for helping!

Unfortunately this formula isn't bringing back the value that I wanted. I want to calculate the total work hours/minutes that go in to completing a job. For example in the first row, the value should be 7:04. Because, although we received the issue at 22:45 the previous night we only began working on it at 8:30. Unfortunately it seems to be when we log an issue outside of work hours and then complete it the following day during work hours.

I want to know if there is any way around this.

Thanks again for the effort, but is there anything else I could do to calculate this?