Informix - no ejecuta el isql

C:\INFORMIX\api\jdbc\isql>javac isql.java

C:\INFORMIX\api\jdbc\isql>java isql
Exception in thread "main" java.lang.NoClassDefFoundError: isql (wrong name: INF
ORMIX/api/jdbc/isql)
at java.lang.ClassLoader.defineClass0(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)

C:\INFORMIX\api\jdbc\isql>