Sorry you're having problems.
Can you tell us what command you used to build voltdb and what command you are using to compile towns.sql?
I'm using Mac OSX 10.9. I tried both the enterprise edition as well as compiled the source from github.
For enterprise edition, I tried copy the voltdb folder to either the home folder or the in the /opt folder.
I added their bin folder path to my .bash_profile file, then in terminal I run the command:
$ voltdb compile towns.sql
I have also tried
$ voltdb compile -o towns.jar towns.sql
In towns.sql, I created table code exactly the same as in the document.
However, from github, I downloaded the source zip folder, extracted it, then I tried to build it using
$ ant dist
For $ ant, after I builded it, I simply copy the folder to my home folder then add its bin folder to the path
For $ ant dist, I used the voltdb-4.2.zip folder int /obj/release folder and copied that to my home folder.
All of which would give me the same error using the voltdb compile command that I mentioned above.
I tired running on debain and ubuntu in virtualbox, it would compiled towns.sql. (Enterprise Edition)
I was able to get these two operating systems to compile because I added java bin directory .bashrc.
I tried to do the same on OS X, by adding the java bin directory to .bash_profile. It still doesn't work and gave me the same error message.
For debain and ubuntu, after compiled, I ran into this error instead when I wanted to run a query.
I tried different version as well. I'm getting the same error.