Problem with GridLayout

Hi everybody, I'm having a problem with the layout of my application.
When I run the following code, I only see one graph in the frame. I'm
sopposed to see "graphNum" graphs in a row.
This part of code runs when I press the "draw graph" button:

   public void run() {
       Graph[] graphs = new Graph[graphNum];
       JFrame frame = new JFrame();
       for(int i=0; i<graphNum; i++){
         graphs[i] = new Graph();
         SliceVal[] sliceValA = new SliceVal[sliceNum];
         for(int j=0;j<sliceNum;j++){
           sliceValA[j] = new SliceVal(new BigDecimal(10.0),
colors[j]);
         }
         graphs[i].setSliceVal(sliceValA);
       }
       JPanel grafPanel = new JPanel();
       graphPanel.setLayout(new GridLayout(1,graphNum));
       for (int i=0; i<graphNum; i++) {
         grafPanel.add(graphs[i]);
       }
       frame.getContentPane().add(graphPanel);
       frame.setSize(300, 200);
       frame.setVisible(true);
    }
  }

SliceVal class holds the value and color of a slice of the pie chart.
Graph class extends JComponent and has a paint() function in it.
I set the values of slices to 10.0 for simplifying the code

Do you see an error in the code above?
I would appreciate any help, thank you.