GPS Receiver for ICOM IC-M422 VHF

[Jude.rich]

Hi there,
I have a IC-M422 VHF radio in my yacht and I am wanting to connect a GPS receiver to it so that it can get a position fix for the DSC function.
The VHF manual states that a “NMEA0183 ver. 2.0 or 3.01 (sentence formatters RMC, GGA, GNS, GLL) compatible GPS receiver is required”
I have a Cobra CM-300-005 GPS receiver which states that it is “compliant to NMEA 0183 Version 4.0”.
The GPS receiver manual states that it will connect to any NMEA0183 compliant VHF, so I expected that it would provide a signal to the IC-M422

Having connected the receiver to the VHF the VHF comes up with the text “No Position”
I know that the GPS receiver is working as it functions fine when connected to a second VHF I have borrowed.

Is this an issue with the different NMEA versions?
If so how can I sort this out so I can use the IC-M422?
Or is it some other issue?

Regards
Richard