Using Serial Port 3 to send GPS values to an external device

[Asso_X_Jewel]

Hi guys,
I'm trying to connect the Serial Port #3 to an external device.
This external device does only accept the NMEA GPRMC messages
I have connected the wire Tx from Skyview D37-6 pinout (Green with orange stripe) to the NMEA input of my device
I have set up the Rate baud to 9600 on the 2 devices : OK
I have checked that the Skview receive the data from the SV-GPS-250 connected on serial port 5 : OK (I can see counter evoluting)

But no transmission data from Serial Port 3 : all counter are freezed to 0, even Sentences errors
What do I miss ?!?
Do I have to use Serial Port 5 Out put ?
Thnak you for your helps

See below :

Serial Port 5 is OK - GPRMC message is OK

Serial Port #3 : nothing happe:

 

[jakej]

For Port 3 try pin 8 not 6 on the D37, that'll should fix it or change the output if it doesn't