If there is no related device driver on your computer, it is hard to connect the device successfully.
Step 1. When connecting the Android device to program, there will be a hint pop up to install the driver first if the driver detected failed.
Step 2. If the driver has been installed successfully but not connect, you are supposed to check whether the driver, which you can find the driver in Computer - Properties - Device Manager - Android Phone, is disabled under Device Manager.
If all processes are on right way, then click Enable and the device will be connected to the computer successfully.