My MMH9xx mux won't communicate with a MMV32/16 series mux.

The MMH mux must have firmware version 3.11 or greater to be able to " network " with the MMV series.
The MMV mux must have firmware version 4.07 or greater to be able to "network"
If the MMH900 is to be " networked " with the MMV series then the source node of the MMH900 has to be 98.
Verify that the node numbers are set correctly.
Make sure that the destination channels are set appropriately for the virtual channels on the MMH900 ( which are set according to how the switches are positioned) .
One of the muxes has remote down on or a bad physical link .
Make sure that switch number 1 is up on the 4 possition dip switch block