Some of the D8B units need the plug-in information reloaded onto the unit. One way to check and see if you need to do this, is to go to the [Setup] menu, and choose [Licensing]. If nothing is listed, then you need to go to Mackie's website and download Service Pack 2, which is located under plug-in downloads for the D8B. If this does not solve your problem, check the manual to make sure you are using the proper procedures, and call technical support if you are.