While generating report, its showing all data including recent and old. i filtered to 1 hr data but it was showing 1hr data but when I created a report it was 1hr data as well as defined one also how to get data for only specific time?
If you limit the time frame of the dashboard to one hour, then the dashlet should automatically receive the same time frame filter and only include that in the report you generated.
I would check to make sure that the incidents dashlet does not have a dashlet specific filter that is overriding the dashboard filter.
My gut instinct is that the following is occurring, the report is showing incidents that were created and active in the past hour. This means that if an incident started before the last hour and have not ended, they will be added to the report. You can check this by looking at your report and finding an incident with an old timestamp. If you do not see a duration or end time it would explain why it is still being included in your report.