Try writing a simple java class to access your database (nothing to do with LCDS), see if you get an error with that.
While using BlazeDS (scaled down version of LCDS) I noticed the JDBC driver to connect to mySQL had to be downloaded for my java classes to access the database. I didn't complete the demo at that URL, but it appears it is using HSQLDB. So I am guessing this is the problem and maybe others will be able to tell you of other potential solutions.
