Using the default values for null should have made your first row in the set be including as the previous value (null) <> the currentvalue

you can also force it to use the via onfirstrecord

Edited by DBlank - 25 Jul 2013 at 3:40am

are you suppressing records?

Here, it basically comes down to we don't know what CR is seeing for the various values.

Break your formula into smaller pieces where you can see each value that is involved in a decision...otherwise you're just guessing at what CR is doing, and many times I've seen the error of my logic by doing this.

So for a first step write a simple formula like:
previous({order})

just to see what CR is 'seeing'.

HTH