custom fields, duration1 from start1 and finish1

[mbbackus]

Now that we have figured out how to copy a network diagram and have multiple ones in the same project, I need to branch out to three sets of dates ...
So the customer knows that the dates from some people are possibly off by a bit (what estimates aren't?). He wants to track them (baseline and start/finish) but also some other dates to compare where the dates would be if the dates were different - without just inputting the new dates in the start/finish columns and see what happens.
So my supervisor thinks we can use start1 and finish1 for the alternate dates. We thought that duration1 would automatically show the duration, but no.

So now I need to know how to write the formula. I am not a programmer. I tried a couple things, but they didn't work. I am not very good at Excel, either, so I have little knowledge base on formulas.
Can anyone tell me how to make duration1 show the timespan between start1 and finish1? Will it use the default calendar I have on this project?

Thanks!

[EINSTEIN_007]

Can you try to first set up one of the extra start and finish fields (e.g. Start1 & Finish1) to coincide with the end points of your custom duration calculation. Then go to Format/Bar Styles and create a new set of bars using the customized fields for the "from" and "to" parameters.

[mbbackus]

Thanks, but we figured it out after a whole bunch of trial and error. It turns out that the calendar was causing the problem. All the directions I could find said to put the calendar in for a formula, but when I put the name of the calendar, I got durations that didn't add up correctly. Finally tried "Project Calendar" and it worked.
So to do this, I highlighted the duration1 column, then went to Tools, Customize, Fields.
In the box, I selected the Formula radio button, then clicked on the Formula button.
In the next box under Function, I selected Date/Time and then ProjDateDiff( date1, date2, calendar ) . Then filled in start1 and finish1 and used Project Calendar for the calendar.
It seems to be working:)
So now in the copy of the Network diagram, we will change the start and finish and duration to start1, finish1 and duration1. Our boss prefers the network diagram to the Gantt chart. It doesn't show as much info, though, so we are improvising.
Thanks again!