UDL prepareChunker not being called

What needs to be in place to have this function called? 

Have the UDChunker prepareChunker(...) function implemented in my ParserFactor and a simple log statement shows the function is never called.  I'm guessing I'm missing something small to give Vertica a hint that it can use the Chunker but can't seem to find anything in the docs.  

Also compiled and ran the example chunker in 

/opt/vertica/sdk/examples/ParserFunctions and the prepareChunker function is never called there as well, which makes me think I have a configuration issue.

It's a basic single-node install of Vertica 7.1.1-0 on RedHat 6.5 nothing else changed.