Calculating working hours betwen two dates

This is my first post on this forum. I am trying to calculate the time difference between two dates. In the attached spreadsheet, I have columns "Date 1" and "Date2". I can take a simple difference of two columns but that gives me the time elapsed. I am trying to find the working hours (M-F, 0800-1700) that elapse between these two dates. I have tried one of the formulas which seem to work for most of the cases but not others, specially when the start or end time is before or after the work hours. Any ideas?

Thanks,
DPathak