Uncaught InvalidValueError: setPosition: not a LatLng or LatLngLiteral: in property lat: not a number
Means you are not passing numbers into the google.maps.LatLng constructor. Per your comment:
/*Information from chromium debugger
trader: Object
geo: Object
lat: "49.014821"
lon: "10.985072"
*/
trader.geo.lat and trader.geo.lon are strings, not numbers. Use parseFloat to convert them to numbers:
var myLatlng = new google.maps.LatLng(parseFloat(trader.geo.lat),parseFloat(trader.geo.lon));