Weird Calculation error: First value only?!!!???

[skyping]

Once again, I am having trouble with a work project and need your help!!!

In the attached simplified workbook there are 3 worksheets.

The data worksheet is simply where all the raw data is stored, and the Bits worksheet is where the data validation will be stored.
The issue is in the Chart worksheet.

This worksheet is a glorified Gantt chart which records the 3 data stages as outlined in the Data worksheet……Current, Amended and Final.
Cells L6 to TM6 show the maximum time lapse of the project BUT for workdays ONLY, as my companies does not work weekends, BUT insist in setting duration days for projects in total days including weekends!!!

In the Chart worksheet, cell A6 is the important cell.

Changing this cell via data validation populates the correct details from the data sheet, BUT the corresponding Gantt does not show exactly what I want.

The problem is that after adding a check column (Col K), the first REAL value is always WRONG!!!!!

Could someone please suggest what is going wrong, and advise how I can stop this error....thus effectively finishes my project!!

Thanks for looking

Skyping.

P.S The test workbook I have attached only shows a sample of the data, so full functionality is not available, but this will not effect the result. Additionality I cant break the links , and as time is running short have simply left them....therefore please dont update.

[6StringJazzer]

This is not a calculation error.

Your timeline in Chart row 6, starting in L6, starts on 12/2/2013, which is forced to be a weekday by your formula. But the start date in cell B8 is 12/1/2013, which is a Sunday. Therefore there is no entry in the Gantt chart for the very first day, and you see only the next 4 days. You have to either make sure all tasks start on a weekday, or allow the calendar to start on the same day that the earliest task starts.

[skyping]

Hi Jeff,

Thanks for the reply.

I thought my calculation in H5 resolved this, as this is where L6 is derived from. I knew that weekend starts would or could cause problems, but I simply cannot seem to work it out!!!! Can you suggest an adaption of formula which would take things into consideration?

Regards,

Skyping