After setting up SharePoint Integrated Reporting in our dev environment we found that when if you tried to set caching on the report caused us to get the following error:

the execute permission was denied on the object ‘xp_sqlagent_notify’


It appears that the course of the problem is down to when installing SSRS in SharePoint integrated mode the service account either doesn’t join the  RSExecRole role or it fails to create the role itself in Master and MSDB. The link below has the steps to setting up the RSExecRole and what permissions to give it.