Help! About PlotXY(const CNiMatrix& xy) problem

[Tony_00700]

please see the code,the result I think it's error.5 points less,please tell me why?????

 long numPtsPerTrace = 5;
 long numTraces = 4;

 double *data;
 data = new double[numTraces * numPtsPerTrace];
 for (int i = 0;i < numTraces * numPtsPerTrace; i++)
 {
  data[i] = i;
 }

 CNiReal64Matrix matrix;
 matrix = CNiReal64Matrix(numTraces, numPtsPerTrace, data);
 for (unsigned int i = 0; i < numTraces; i++)
 {
  for(unsigned int j = 0; j< numPtsPerTrace; j++)
  {
   TRACE("%f ",matrix(i,j));
  }
  TRACE("\n");
 }

 m_Graph.PlotXY(matrix);