[Rivet] undefined symbol: _ZNK5Rivet8Analysis6getLogEv

[Emily Nurse]

Hi again Riveters,

I am trying to run a routine built using the pluggable analyses documented here:
http://projects.hepforge.org/rivet/trac/wiki/WritingAnAnalysis

but I get the runtime error: 
Cannot open ./libRivetMyAnalysis.so: ./libRivetMyAnalysis.so: undefined symbol: _ZNK5Rivet8Analysis6getLogEv

Has anyone seen this before?

Thanks,
Emily.