orbit-idl (what do these errors mean?)

[Richard Andrews <richarda ixla com au>]

Just managed to get orbitCPP-0.29 to build.
I've got ORBit-0.5.4-helix

When I try to compile a test I get this

orbit-idl -lc++ test.idl

** WARNING **: Module load failed: /usr/lib/orbit-idl/liborbit-idl-c++-backend.so: undefined symbol: __vt_9exception

** CRITICAL **: file orbit-idl-driver.c: line 50 (orbit_idl_to_backend): assertion `binfo && binfo->op_output' failed.

** WARNING **: test.idl compilation failed


What do these errors mean?