Problems with Arming function MAVlink

Hello there
I am using MatMav for my Pixhawk 2.1.
I downloaded the files and opened it in Matlab.

I tried a few things and they work.
BUT: If I try to arm my object, an error occurs and I have no idea how to fix this.
Can somebody help me?

The Matlab Code (from the MatMav Package)

%% create object

number_of_targets=1;
mav=MatMav(number_of_targets);

% find available ports
mav.findPorts();

%%
mav.set_COMPORT(‘COM6’);
mav.set_BAUDRATE(57600);
mav.ConnectSerial();

%%
target=1;
start=1;
mav.Arm(target,start); // HERE the following error occurs:

Undefined function ‘mavlink’ for input arguments of type ‘char’.

Error in MatMav/Arm (line 1530)
[Buff,~]=mavlink(‘Arming’, agent, flag);

Error in Untitled (line 19)
mav.Arm(target,start);