SIMULINK Attempt to extract field 'ConnectTCPIP' from 'mxArray'.

Hello, I am trying to connect a PI Hexapod Robot via TCPIP by SIMULINK MATLAB Function. For this purpose following code has been written.

function y =fcn(a)
coder.extrinsic('PI_GCS_Controller')
persistent Controller
if isempty(Controller)
  Controller = PI_GCS_Controller();  
  ip = '169.254.10.196';
  port = 50000;      
  Controller = Controller.ConnectTCPIP(ip, port);
end
y=a+5;
end

I do not encounter any problem when I try MATLAB instead of SIMULINK. However, when trying on SIMULINK MATLAB Function with the code above, following error shows up:

Attempt to extract field 'ConnectTCPIP' from 'mxArray'.

I searched for it and what I found is as follows: Link 1, Link 2

The solution is recommended as preinitializing the variable. But I already initialized "Controller" as "PI_GCS_Controller()". So I do not understand the problem. "ConnectTCPIP" function is inside the "@PI_GCS_Controller" folder which is at the Current folder of MATLAB.

If needed, the "ConnectTCPIP" function written by PI is as follows:

if(~libisloaded(c.libalias))
  c = LoadGCSDLL(c);
end
FunctionName = 'PI_ConnectTCPIP';
if(any(strcmp(FunctionName,c.dllfunctions)))
  try
    [c.ID] = calllib(c.libalias,FunctionName,szHostName,nPort);
    if(c.ID<0)
      iError = GetError(c);
      szDesc = TranslateError(c,iError);
      error(szDesc);
    end
  catch
    rethrow(lasterror);
  end
else
  error('%s not found',FunctionName);
end

Why do I get error? Thanks in advance..