You can only access the features of the Breathe-Link software with a valid POWERbreathe K-Series device that is connected and synchronised with the software. Close the Breathe-Link software and connect a valid POWERbreathe K-Series device, then start up Breathe-Link software. Make sure you have correctly installed the drivers.
Use the USB port you used when you first connected the POWERbreathe device to the Breath-Link software. In some instances the USB driver for the Breathe-Link software only recognize the POWERbreathe device when connected to the same USB port when it was first installed.