Error mesage in matlab regarding getdata function in data acquisition toolbox?

Error mesage in matlab regarding getdata function in data acquisition
toolbox?

I am trying to get real time data from a microphone in matlab, but I keep
on getting this error message
Error in analoginput/getdata (line 196)
varargout{1}=getdata(uddobj,samples,dataformat);
Error in speech_Detection (line 28)
data = getdata(AI);
Here is my code
AI = analoginput('winsound', 0);
addchannel(AI, 1);
Fs = 44100;
set(AI, 'SampleRate',Fs);
set(AI, 'SamplesPerTrigger',duration*Fs);
for i = 1: num_Frames
i
start(AI);
data = getdata(AI);