Lifecycle Report Error

I followed religiously the following instructions from one of the Percusion docs: Customizing_Content_Explorer.

To modify the Content By Community report:
1 Copy the CommunityContent resource from the sys_reports application to the rx_reports application.
a) In the Rhythmyx Workbench, open the sys_reports application.
b) Select the CommunityContent resource.
c) Click the copy button.
d) Open the rx_reports application.
e) Click the paste button.
Rhythmyx adds the CommunityContent resource to the sys_reports application.
2 Map the CONTENTSTATUS.CHECKEDOUTUSERNAME column to a new node in the DTD, named Checked_Out_To:
a) Double-click on the CommunityContent resource.
Rhythmyx opens the Mapper for the resource.
b) Find the CONTENTSTATUS.CHECKEDOUTUSERNAME column and drag it to the first empty row in Back-end column of the Mapper.
c) Double-click in the XML column of the Mapper and add the new DTD element. This element must be a child of the Content element, so enter the new element as follows:
Remember to add the underscores. The macros in the LifecycleAnalysis.xls workbook will replace them with spaces, but the underscores are required in Rhythmyx.
d) To test your modification, start a browser session and query the resource. Enter the following value in the Address field:

I get the following message on going to the above URL:

The data set associated with the request for (/Rhythmyx/rx_reports/ContentCommunity.xml) submitted by session id 87d8caee6181899d7db41aaabed8fd65d350bd12 could not be found in the application (rx_reports).

Any clues please??