I recently observed that one of my custom alert reports didn’t show the correct timestamp for each alert. After some troubleshooting I found out that this report didn’t compensate for time zones. Since data are stored as GMT in the Data Warehouse the time zone the control picker parameters needs to be remunerated for this.
Looking in the code snippet you have to paste into your report to get the smart parameters I found the function called “ToReportDate” which was what I was looking for.
My replacement in the Queryparameters looked like this:
=Code.ToReportDate(Fields!Alert_Date.Value)
You can read more about Report authoring here: http://technet.microsoft.com/en-us/library/dd362600.aspx