Restriction of data for a week using datatime parameters in SSRS Report.

I am building a report in Micrososft SQL Reporting Services and, I have two date fields, startDate and endDate.

I need to limit the date range, only a week of data every time. For example, if startDate is 2013/01/01 and endDate is 2013/07/01.

if user enters more then one week of dates in calender it should pop a message.

is it possible in SSRS? if so then How can I do that?

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Regards, Chirag Patel (ETL Engineer)