No audio input device detected

setpref('dsp','portaudioHostApi',3);
microphone = audioDeviceReader('Driver', 'ASIO', 'SampleRate', 48000);
speaker = audioDeviceWriter('Driver', 'ASIO', 'SampleRate', 48000, 'BufferSize', 1024);
devicesIn = getAudioDevices(microphone)
devicesOut = getAudioDevices(speaker)

tic;
while (toc<30)
    audio = microphone();
    speaker(audio);
end
release(microphone);
release(speaker);

the above code resulted in the error 'No audio input device detected', even though i have an asio supported audio interface plugged in. How do I solve this problem?