Before starting or accessing a report, you must apply a time period. The given period can be accessed on the top right of the report.
By default, for a campaign or program, the filter period is set to the start and end date of the program or campaign. For a delivery, the start date corresponds to the sent date and the end date to the sent date plus 7 days.
To modify the filter, select a start date and a period or use the pre-set time period such as last week, two months ago, etc.