Step 1: prepare the phone:

Make sure you have selected the correct USB mode at your phone: Connectivity -> USB settings -> Default Connection to 'Data/Fax Connection'.
If you change that setting you have to unplug the phone plug it in again.

Step 2: install the drivers

In Mobile Master start the Setup Wizard (e.g. menu Tools-> Setup Wizard) and click at 'Have you installed the driver for the cable?'. A wizard will guide you through the installation.