[vtkusers] no matching function for call to vtkPolyData::GetNumberofPoints()

[Vetria Byrd]

I have written a simple program (Reader.cxx) to read in PolyData from a file and 
print the number of points found in the data file.  I have included 
vtkPolyData.h and vtkPolyDataReader.h but I am getting the following error 
message:

Building object file Reader.o...
Reader/Reader.cxx: In function `int main(...)':
Reader/Reader.cxx:26: no matching function for call to 
`vtkPolyData::GetNumberofPoints ()'
make[1]: *** [Reader.o] Error 1
make: *** [default_target] Error 2


I don't understand what the problem is . . .
Here's the code:

#include "vtkPolyData.h"
#include "vtkPolyDataReader.h"

void main ()
{


// read data from file
  vtkPolyDataReader *PolyDataReader = vtkPolyDataReader::New();
  vtkPolyData *PolyData;
  
  PolyDataReader->SetFileName("Data/honolulu.vtk");
  PolyDataReader->Update();
  PolyData = PolyDataReader->GetOutput();
  printf("\n pts read: %d\n",PolyData->GetNumberofPoints() );
      
  //
  // Free up any objects created
  //
  PolyData->Delete();
  PolyDataReader->Delete();
  
  
  return 0;      
}