I mentioned back in 2008 that Web Reports with OLAP source can drill-through to detail (or display the raw data records for the corresponding cross tabular cell) only after the source information map has drill-through to detail enabled. Well, there are several other areas that also could disable this capability for your users so I would like to provide a more extensive list of what to consider when enabling OLAP drill-through.

1. SAS Management Console User Manager Plug-in includes three Web Report Studio roles with capabilities available for OLAP viewing and drill-through. Administrators can choose to disable the OLAP drill-through functionality across the entire system. This capability is useful for environments with limited resources to handle OLAP queries or organizations that might use OLAP to only summarize secure detail records.
2. The SAS OLAP Cube needs to include a defined drill-through table. In OLAP Cube studio this is a GUI titled 'Cube Designer Drill-through'. Having this functionality at the OLAP build level allows for the data administrator to include a different table than the source or not define a table at all.
3. From Information Map Studio, once the information map is saved the properties can be modified to allow drill-through capability. (This is unchecked by default.) Data administrators could prefer that the drill-through is available on the cube from direct use (via Enterprise Guide or Add-in to MS Office) but that it is not available to Web Report Studio users who view the cube through the information map.

A couple additional notes: After enabling drill-through for a cube and you still have trouble accessing the detail data then check on the following items. (This is just the three most common items I have seen, by all means this is not an extensive list.)

1. If a different data table was selected for drill through than the source, all levels used in the drill-through report must exist in the drill-through data table for a successful query.
2. The libref for the drill-through table is not assigned to the OLAP Server. http://support.sas.com/kb/12/215.html
3. By default all new metadata items should set SAS Trusted User (as a member of the SAS General Services group) READMETADATA access. However if the administrator has modified or created a new Default ACT, refer to the documented requirement that SAS Trusted User has READMETADATA access on the drill through tables. http://support.sas.com/documentation/cdl/en/olapug/59574/HTML/default/viewer.htm#a003212372.htm