V-Control 4 has a lot of changes under the hood compared to v3. It is much more Event driven. There are also some script commands in V4 that are not available in V3. If you export a V4 device and import it in V3, then it works unless the driver does not use any of the new scripting commands. After import in V3, go to device editor and click compile. If there is no error, then the driver should work.