Calculating Elapsed time minus holidays and weekends

The attached spreadsheet has a formula in column L that I need help with.

I am looking to find the elapsed time in hh:mm between the "start date" and the "resolved date". I need to make sure to eliminate any standard holidays and weekends and only calculate for a standard 8a-5p day. Please take a look at what I have so far. Any help would be greatly appreciated!

Using:
=IF(OR($L101="",$M101=""),"",(NETWORKDAYS($W101,$X101)-2)*($AA$2107-$AA$2106)+MAX(0,$AA$2107-MAX(TIME(HOUR($W101),MINUTE($W101),SECOND($W101)),$AA$2106))+MAX(0,MIN(TIME(HOUR($X101),MINUTE($X101),SECOND($X101)),$AA$2107)-$AA$2106))

Thank you, Glenn!!!

Yes, it is normal for the start date to start outside of normal business hours. And I should have deleted those rows with blanks for hte start dates.

So for rows N2 to N5 is there a specific format I need to put in those cells for the holidays? For4 example, should it look like "2/2/2015 9:14:39 AM" with time and all, or can I just put a date?