Frequent No Pilot Alarms

[Aquadesiac]

Enclosing schematic,
Powersources are: SPX gets 12V power in and out to Pump.
SeaTalkng converter gets power from SPX, assumption since disconnecting the SPX connection puts out green light.
The other SeaTalkng block gets power in with Black/Red (B/R) seatalk cable.
There is on termination plug on each block.
Connection between blocks with Black/Blue cable.

If I try to select GPS source on MFD I get error message "Data Selection not Possible" THe following deveices are preventing data source selection spx10 S/N
please see your user manual for details.

When disabling internal GPS nothing seemed to happen, could it then get the GPS info from antenna that is connected to STng. (not sea trialed anything today)
If I disconnect the GPS antenna connected to STng I get message of no heading info.

Appreciate all the help

H