Enable Magento logging/debugging

1. Enable system wide logging under System > Configuration > Developer > Enable Logging 
2. Also enable specific logging specific to this extension under System > Configuration > Payment Methods > MageBase DPS (enable for PxPay and PxPost accordingly) This will create entries in the database table magebase_dps_debug for all communication with the DPS servers. You will also get a new log file under var/log starting with magebasedps.