matlab serial communication A timeout occurred before the Terminator was reached

Hi

I am planning to send some data from pic to matlab and plot the same accordingly.Pic code was working fine.I simulated it on proteus and found that the data is sending correctly.But the issue was with Matlab.It gives the following error "a timeout occured before the terminator has reached"

how to fix the problem

if true
 %%Serial Data Logger
      % Yu Hin Hau
      % 7/9/2013
      % **CLOSE PLOT TO END SESSION

        clear
        clc

        %User Defined Properties 
        serialPort = 'COM11';            % define COM port #
        plotTitle = 'Serial Data Log';  % plot title
        xLabel = 'Elapsed Time (s)';    % x-axis label
        yLabel = 'Data';                % y-axis label
        plotGrid = 'on';                % 'off' to turn off grid
        min = -1.5;                     % set y-min
        max = 1.5;                      % set y-max
        scrollWidth = 10;               % display period in plot, plot entire data log if <= 0
        delay = .01;                    % make sure sample faster than resolution

        %Define Function Variables
        time = 0;
        data = 0;
        count = 0;

        %Set up Plot
        plotGraph = plot(time,data,'-mo',...
                        'LineWidth',1,...
                        'MarkerEdgeColor','k',...
                        'MarkerFaceColor',[.49 1 .63],...
                        'MarkerSize',2);

        title(plotTitle,'FontSize',25);
        xlabel(xLabel,'FontSize',15);
        ylabel(yLabel,'FontSize',15);
        axis([0 10 min max]);
        grid(plotGrid);

        %Open Serial COM Port
        s = serial(serialPort);
        set(s,'BaudRate',9600,'Terminator','LF/CR','Parity','None');
        disp('Close Plot to End Session');
        fopen(s);

        tic

        while ishandle(plotGraph) %Loop when Plot is Active
             %pause(2);
            dat = fscanf(s,'%f'); %Read Data from Serial as Float
          pause(0.5);
            if(~isempty(dat) && isfloat(dat)) %Make sure Data Type is Correct        
                count = count + 1;    
                time(count) = toc;    %Extract Elapsed Time
                data(count) = dat(1); %Extract 1st Data Element         

                %Set Axis according to Scroll Width
                if(scrollWidth > 0)
                set(plotGraph,'XData',time(time > time(count)-scrollWidth),'YData',data(time > time(count)-scrollWidth));
                axis([time(count)-scrollWidth time(count) min max]);
                else
                set(plotGraph,'XData',time,'YData',data);
                axis([0 time(count) min max]);
                end

                %Allow MATLAB to Update Plot
                pause(delay);
            end
        end

        %Close Serial COM Port and Delete useless Variables
        fclose(s);
        clear count dat delay max min plotGraph plotGrid plotTitle s ...
                scrollWidth serialPort xLabel yLabel;

        disp('Session Terminated...');

end

[Walter Roberson]

Did you look at hardware flow control?