find an image in a big image

I am trying to find a sample image patternC :

In my large image like :

To accomplish this task, i have coded this:

clc;

htm=vision.TemplateMatcher;
 hmi = vision.MarkerInserter('Size', 10, ...
    'Fill', true, 'FillColor', 'black', 'Opacity', 0.75); 

% smallSubImage = fullfile(matlabroot, '\toolbox\images\imdemos\1.bmp');
% I = imread(smallSubImage);
I = imread('6.tif');

% Input image
   I = I(:,:,:);  
% Use grayscale data for the search

[rows, columns, numberOfColorChannels] = size(I);
if numberOfColorChannels == 3
  I = rgb2gray(I);

    if rows > 200 && columns > 200
      I = I(1:rows,1:columns,:); % Crop all 3 channels.
    end
  else
    if rows > 200 && columns > 200
      I = I(1:rows,1:columns); % Crop single channel.

    end
  end

display(rows);
display(columns);

Igray = imread('patternC.tif');
[rows, columns, numberOfColorChannels] = size(Igray);
if numberOfColorChannels == 3
  Igray = rgb2gray(Igray);    
else  
  Igray = Igray(1:rows,1:columns); % Crop single channel. 
end

% Use a second similar chip as the template
  T = Igray;  

% Find the [x y] coordinates of the chip's center
  Loc=step(htm,Igray,T);  
display(Loc);
display(NVALS);
display(NVALID);
% Mark the location on the image using Black disc
  J = step(hmi, I, Loc);

imshow(T); title('Template');
figure; imshow(J); title('Marked target');

display('process completed');

But the output is:

The template is detected on the LEFT TOP corner(A Black Circle) of the image.

I am new in matlab. What is the matter here? Which things I have to take in mind?

[David Young]

What does the function step do?

[Image Analyst]

I'm not sure I see a black circle. I see something like a black asterisk. And what does your code mean when it says "Mark the location on the image using white disc"? How would you see a white disc on a white paper?

[Abdur Rahim]

I am not so sure. But seems like it steps onward of template matching method in vision.templateMatcher. You can see this link below:

http://www.mathworks.com/help/vision/ref/vision.templatematcherclass.html

I have used the example code of this link. @David Young

[Abdur Rahim]

The Big image is really big here. The output window is just showing 25% view. So the black circle is looking small and asterisk like. Its a black circle I defined in my 2nd(& 3rd) line of code. And the quote was a mistake. It is black disk and I edited the question. Yes, I cannot see a white disc on a white paper.

[Walter Roberson]

How could the output possibly be that? The date of the page changes, the QR code goes away, the list of digits along the left side got replaced by a linear barcode ???