Have you installed vertica driver s on TS too? if you are connecting to vertica inorder to render the report, the drivers and any dsns you created need to be on the server also . other wise it would throw an error for you
This could be for all sorts of reasons...
Lets start with the basics - version of desktop and version of server? are they different?
and are latest drivers installed?
Have a look at this thread > Tabcmd get pdf errors although initially it doesn't appear related, a lot of the advice from myself and Toby will be useful for you.