SSRS on SharePoint: Check for Subscription failure issue

Question

Hi all,

I am dealing with an SSRS data-driven subscription failure issue. I am using SQL Server 2008 R2 with its reporting services run on SharePoint integration mode (in a SharePoint 2010 server): As shown above, this subscription instance generated 27 reports with 3 errors (it turned out that 3 out of 27 reports were skipped somehow).

In the SQL 2008 server I could find the ExecutionLog3 but found it not so useful....

It is also said that one could find reporting services logs files under \Program Files\Microsoft SQL Server\MSRS13.MSSQLSERVER\Reporting Services\LogFiles, but in my case there is no such folder called "Reporting Services" in the machine running SQL Server 2008:

Any ideas of how to proceed checking why 3 out of 27 reports of this subscription run failed? Many thanks in advance.

Ricky