> Compiling good, but when I'm try to execute, system show error
> message "Unable to load driver"
> ...
> String driverName = "org.firebirdsql.jdbc.FBDriver";
> ...
> try { Class.forName ("driverName"); }

What about replacing last line with

try { Class.forName (driverName); }

(remove quotes, you were trying to load driver called "driverName").

Roman