Record value depending of the next record

Hi,
I am trying to do something with Crystal Reports 9, but I am not sure if it is possible to do it...

how_long is the field I want to add
...depending of how many consecutive True value there is in the active field, I want to know for how many days it is True

when it is False...I put no value in the how_long record

SEE example.txt

I thought I could use the function Next(), but I need to go further than the next record

Any way to do this?
Would it be with a subreport? I don't know
Thanks for your help

Michaelput a formula which gives 1 when active is true then use running total and reset it when value changes , hope it workss..