I want to get sales value for 2 custom periods - the problem is that
periods is not simple ( like compare one week to another) but in ex.
compare 3 days to 2 months

How can i do that ?

You might find this recent discussion of "Time Ranges in AS 2005" from
Chris Webb's blog relevant:

http://spaces.msn.com/members/cwebbbi/Blog/cns!1pi7ETChsJ1un_2s41jm9Iyg!
262.entry
Basically he needs two Period dimensions in his cube, from which the
user can select individual members or ranges, allowing the user to
compare values for a measure across these two different Period
selections. For example the user might want to compare Sales in January
1997 with Sales in February and March 1997 combined.
...

- Deepak

Deepak Puri
Microsoft MVP - SQL Server

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