Error Message for Thermocouple: Subsystem in use

I'm trying to control my theromcouple using MATLAB. However, I always receive the following error message:

"Error using Thermocouple (line 4)

dt Error 20:

Subsystem in use"

However, the thermocouple is only connected to my computer, so I can't understand why the "subsystem" would be in use. Here's my code:

devices = daq.getDevices

s = daq.createSession('dt');

addAnalogInputChannel(s,'DT9828(00)',0, 'Voltage');

s.Rate = 1

tc = s.Channels(1);

set(tc)

[data,time] = s.startForeground();

plot(time, data)

xlabel('Time (secs)');

ylabel('Voltage (V)');

Final note: I've been following the instructions on this article: https://www.mathworks.com/help/daq/examples/acquire-temperature-data-from-a-thermocouple.html