Ensure that the SQL Anywhere JDBC 4.0 driver is in your class file path.
set classpath=%IQDIR%\java\sajdbc4.jar;%classpath%
The JDBC 4.0 driver takes advantage of the new automatic JDBC driver registration. The driver is automatically loaded at execution startup when it is in the class file path.
The Java component of the SQL Anywhere JDBC 4.0 driver is included in the sajdbc4.jar file installed into the Java subdirectory of your SAP Sybase IQ installation. For Windows, the native component is dbjdbc16.dll in the bin32 or bin64 subdirectory of your SAP Sybase IQ installation; for Unix, the native component is libdbjdbc16.so. This component must be in the system path.