S-function Error cuase?

Hello every one I have a model in simulink :

S-Function :

if true
  function [sys,x0,str,ts] = pt1sfun(t,x,u,flag,T)
A = [-1/T];              
B = [ 1/T];               
C = [ 1  ];               
D = [ 0  ];                                          
switch flag,

%%%%%%%%%%%%%%%%%%
% Initialization %
%%%%%%%%%%%%%%%%%%
case 0,
  [sys,x0,str,ts]=mdlInitializeSizes(A,B,C,D);

%%%%%%%%%%%%%%%
% Derivatives %
%%%%%%%%%%%%%%%
case 1,
  sys=mdlDerivatives(t,x,u,A,B,C,D);

%%%%%%%%%%%
% Outputs %
%%%%%%%%%%%
case 3,
  sys=mdlOutputs(t,x,u,A,B,C,D);

 % Nicht verwendete Flags   
 case {2, 4, 9},
    sys=[]; 

%%%%%%%%%%%%%%%%%%%%
% Unexpected flags %
%%%%%%%%%%%%%%%%%%%%
otherwise                                       % Fehlerbehandlung
  error(['Unhandled flag = ',num2str(flag)]);
%end
% end pt1sfun
%
%=============================================================================
% mdlInitializeSizes
%=============================================================================
%
function [sys,x0,str,ts]=mdlInitializeSizes(A,B,C,D)
sizes = simsizes;
sizes.NumContStates  = size(A,1);                                     
sizes.NumDiscStates  = 0;           
sizes.NumOutputs     = size(C,1);
sizes.NumInputs      = size(B,1);  
sizes.DirFeedthrough = 0;
sizes.NumSampleTimes = 1;    
sys = simsizes(sizes);
% initialize the initial conditions
x0  = zeros(size(A,1),1);           % Anfangszustand: x0 = 0
% str is always an empty matrix
str = [];
%
% initialize the array of sample times; in diesem Beispiel ist die
% Abtastzeit kontinuierlich, daher wird ts und der zugehoerige
% Offset zu Null gesetzt.
%
ts  = [0 0];
% end mdlInitializeSizes
%
%=============================================================================
% mdlDerivatives
% Return the derivatives for the continuous states.
%=============================================================================
%
function sys=mdlDerivatives(t,x,u,A,B,C,D)
sys = A*x + B*u;                     % Berechnung von der Ableitungen xpunkt
% end mdlDerivatives
%%=============================================================================
% Return the block outputs.
%=============================================================================
%
function sys=mdlOutputs(t,x,u,A,B,C,D)
sys = C*x + D*u;                     % Berechnung des Ausgangsvektors y
% end mdlOutputs
end

I got this error after running;Why?

.. ..

Here T is fix(T = 0.01;)

Another question: If T be variable (0.1<T<10) from another part of simulink How can I define T in S-Function?