Best way to get last 2 hour in report studio

[priya1988nath]

Hi all ,
I am using audit database to check what are reports failed in last 2 hours.I have used extract hour for this .But not satisfied with this code .Can you please let me know the best way to subtract 2 hours from  time stamp field?
I have already tried add_hour also . but it didn't worked out

[sdf]

did you cast your add_hour to timestamp???