Calculating handling times between two dates, in hours, excluding holidays/weekends

Hi,

I'm trying to calculate service level handling times on a set of incoming reports I receive. The number of hours:minutes between a "Created Date" and a "Resolved Date". While also excluding Saturday-Sunday weekends and specific holiday days in the cumulative totals. The business hours equal to 07:00AM to 19:00PM Monday-Friday. The "Created Date" in my case can be on Saturday-Sundays and the holiday days. Effectively the reports are generated 24/7 but will only be 'handled' during weekday business hours.

This thread from mrcexcel.com got me well on my way using =NETWORKDAYS.

I'm currently using this formula

Please Login or Register  to view this content.

A2 = Created Date
B2 = Resolve Date
E2-E7 = Holidays

But it seems it's not properly calculating the handling times in some cases. The formula just returns a set of "########"

I've attached an example workbook with my date data, I'm looking for insight in to why the few "########" entries happen and how to fix them.
I'm using Excel 365 and European date formatting for reference.

Take for instance C927. The times are only 8 minutes apart and both times are outside your working hours. If I change the time in cell B927 to 8:21 I get 1:21.
I haven't studied the formula so I don't know how it works, but it seems to be creating a negative number which is why you are getting the ##'s.

EDIT:
I believe I have worked out a solution for you.

In C2:

Formula:

Please Login or Register  to view this content.

If your original request is fulfilled please click the Thread Tools drop down box above your first post and choose solved.

If you are happy with my help, please consider clicking the add reputation button in the lower left hand corner of this post.

Thank you for the rep. points, the feedback and marking the thread as solved.