Just figured it out w/ someone else's posting from last year...

 

"Look at the fine print on the power supplies for the number of amps they output.  The ones that can drive the port replicators put out 4.62A.  While the ones for just the laptop put out something like 3A.  "

 

The d/port replicator works fine now w/ the right power adaptor.

I'm having this same problem w/ an eBay purchased replicator.  I have one at work that works with this power adapter, so I'm not sure what the difference between the replicators is.