Paste link not available

I'm using Publisher 2003. I have two differently-organised versions of the
same document and want to set one up as the master - where I'll make any
changes - and one as the slave where any changes are replicated. My idea for
achieving this is to paste each object from the master document as linked
objects in the slave.

The help files suggest that I should be able to copy objects from one
document and use Paste Special > Paste Link to put them into the other;
however, when I click on Paste Special, the "Paste Link" is greyed out.

The process looks very straightforward in theory and I'm convinced that I'm
following the simple instructions correctly - but I'm hoping I'm wrong! I've
even tried creating a brand new publication containing just one object and
attempting to paste this as a link in a second new publication - and even
this doesn't work. Does anyone know what's going on?