Invalid operands to binary expression ('RadioDevice' and 'const RadioDevice')

I stuck badly on this issue, I am trying to find an object in list using find(). Below is the code:

std::vector<RadioDevice> radioDevices;
public:
void add(CartesianLocation location, std::list<RadioSignal<RadioDevice>> observedSignals){
    for(RadioSignal<RadioDevice> radioSignal : observedSignals) {
        if (std::find(radioDevices.begin(),
                      radioDevices.end(),
                      radioSignal.getRadioDevice()) != radioDevices.end()) {
            radioDevices.push_back(radioSignal.getRadioDevice());
        }
    }
}

RadioSignal extends RadioDevice which is an pure abstract class. I am getting the mentioned error at if (*__first == __value_) in find()