Can't get my REST call to work

I’m also having issues, but my remote site setting is correct. The URL looks like it is correct, as it is rendering the JSON: 
http://developer.itsmarta.com/RealtimeTrain/RestServiceNextTrain/GetRealtimeArrivals?apikey=8c49d528-5bdc-4b37-a2a8-ea553622a8db 

What am I missing??