Filter 3 week lookahed

Hi!

Probably this is a simple thing, but I couldn’t implement it.

My project has a data date of 20.08.2009.

- Primavera has a simple filter for 2 weeks lookahed. I copied it and I rename it to 3 weeks lookahed and defined the time frame to 21.09.2009 until 11.10.2009 (3 weeks).
I notice that same activities were shown and were not right (activities that finished until 20.09.2009 with status as being in progress). I realize that just defining the period dates (is within range of) and the activity status (in progress) was not enough.

- I implemented a new filter, now defining a start date on 21.09.2009 or a finish date on 11.10.2009.
It worked better, but after some time I realize that activities that are outside the period range (crossing this time frame) were not shown (activities that started on 10.08.2009 and finish on 15.10.2009 and activities that will start on 19.09.2009 and finished on 18.10.2009).

I pretend a filter that can show me all the activities that are happening or will start or will finish in a certain period after the data date of the project.

Have you a better idea how to implement the filter?

Tank you for your support.