what is the shape of the wave form of the data acquired using Matlab session based command with the help of NI DAQ 6343

It produce spike wave instead of sine wave. Why?

s = daq.createSession('ni');

ch = s.addAnalogInputChannel('Dev5',[0 1 2 3], 'Voltage');

s.Rate = 1000;% how fast do you want to acquire the data

s.DurationInSeconds = 1; % acquisition total time

[data,time] = s.startForeground