What does the status message "not present" mean in MAX?

Hello,

     I have two instruments, a Burleigh WA-1000 wavemeter and a Tektronicx TDS 2012 B Oscilloscope, connected to a GPIB - USB converter which then goes into my computer. The MAX panel "sees" both of these instruments but designates their status as "not present" and I always get the timeout error when trying to communicate with them.

   If anyone either knows what's wrong or can give me some things to troubleshoot it would be a real help.

Thanks.