This could be caused by a communication problem between the instrument and the computer.  Perhaps the instrument is not properly connected to the computer or to the cable, or the hardware port has not been setup properly.  Verify that the instrument is connected to the computer using the cable supplied by Intoximeters. It is possible that the cable is broken internally, preventing proper two way communication. If your computer does not have a 9 Pin serial port, you may need to use a USB to Serial Adapter. It is possible for this device to be physically installed but not properly configured. Verify that the USB to serial adapter drivers are properly installed. These files will be available from the manufacturer of the adapter, and may be on a CD-ROM packaged with the device, or on the manufacturer's website for download.  If the cable and adapter (if applicable) are both physically connected and properly installed, you can then perform a communication test which is built into Alco-Sensor IV @Work. This can be done in the configuration menu, accessable by clicking "Configure" from the main menu. Then click on the HARDWARE tab. In the column labeled ASIV, verify that the com port which is available, as indicated by black text rather than grey, is also the one which is selected, as indicated by the button being filled in, rather than empty. Then click the TEST button directly below that column and follow the on-screen instructions. There may be more than one available port so you may have to try all of them. There may also be no available ports, in which case you may have to change which port your USB to serial adapter is assigned to. This can be done in the Windows Device manager. The USB adapter should be found under the PORTS heading, and the assigned com port will be in parenthesis after the description. Alco-Sensor IV @Work offers 6 possible ports, (com 1 through com 6), so if the adapter is set for any port higher than 6, it can be changed by double clicking on the item, selecting PORT SETTINGS and then ADVANCED. Once both Windows and @Work are in agreement which port you are using, the TEST function should pass.