Calculate total hours worked between 2 date/time stamps ignoring weekends and holidays

Hello all. I have attached my test file so you can see the problems I am having. I found the formula online after trying several others and works better than the others but is still not totally working. The formula is in column C and the desired results are in column E. As you can see, I broke the total date range out into individual days so I could validate the formula for each day and in row 28, I have the entire date range. The problem values are in red. I tried a few other situations which also seemed to have problems calculating correctly. Can someone take a look and correct the formula or offer one that works in all the situations on the sheet?

Thanks,
Andrew