What am I missing?

We're running SW2014 with Workgroup PDM.  Our PDM Administrator has enabled the revision tables for the Workgroup.  In the TOOLS>OPTIONS>DOCUMENT PROPERTIES>TABLES>REVISION window, I see that Alpha/numerical control options are greyed out, and there is a note "Revision driven from SolidWorks Workgroup PDM."  When I add a revision table to a drawing, it appears as just the top two header rows (REVISIONS across the top, then ZONE, REV., DESCRIPTION, DATE, APPROVED in the second row).  What I expect to happen is that when I check in this drawing, a row will be automatically added to the table, with the REV, DESCRIPTION, and DATE fields auto-filled from the PDM properties.  However, in practice nothing happens.  When I subsequently check out the drawing, the Rev in the title block (linked to the "Revision" custom property in the drawing) updates correctly, but there is no change to the revision table.  Additionally, I can right-click the revision block, and manually add a revision, which does not follow the PDM revision scheme, and overwrites the custom property linked in the title block. 

What am I doing wrong?  I'm sure it's something simple I'm overlooking, but I am at my wits' end.  Thanks!