Can't read descriptor value

[nielsswinkels]

When I have discovered descriptors, I try to do readValue on the descriptor but it keeps giving me this error (on android). (Even though I can see the readValue function in proto inside the object)

console.log(descriptors[descriptorIndex]);
descriptors[descriptorIndex].readValue(function(error, data){
   console.log("descriptor readValue:"+data);
});

Am I doing something wrong or is this a bug?