GTN Sim Variables

Hi All,

I would like to be able to access the Simulation Variables mentioned in the reference manual but have been unable to do so.

I am not overly familiar with  referencing  3rd party (non P3D) variables so I'm probably doing something glaringly wrong.

Here's my setup code:-

SimConnect_MapClientDataNameToID ( hSimConnect, "rxp.gps.cross_track_nm_1", GTN_ID_XTRACK);  // trying to read cross track var

SimConnect_AddToClientDataDefinition ( hSimConnect, CLIENT_DATA_DEF, SIMCONNECT_CLIENTDATAOFFSET_AUTO, SIMCONNECT_DATATYPE_FLOAT64);

SimConnect_RequestClientData ( hSimConnect, GTN_ID_XTRACK,  CLIENT_REF , CLIENT_DATA_DEF, SIMCONNECT_CLIENT_DATA_PERIOD_SECOND);

As far as I know , this is all I should be doing to get sent a message: SIMCONNECT_RECV_ID_CLIENT_DATA with data within for  xtrack. 

If I can get this working then I can expand to get multiple data out.

But I get nothing. 

Can anybody point out what I am doing wrong. Am I referencing the GTN variables correctly? Is the code sequence in correct ?

I'd be grateful for any help.

Cheers.