Object reference not set to an instance of an object

I am developing a web application and I wanted to print PDF files on the server printer such that I would like to control the printer settings. For that I created a component and is getting the following error:
Object reference not set to an instance of an object

My code in the component looks like this:

Code:

---

public string PrintPDF(Acrobat.CAcroPDPage pdPage, int numPg)
{
Type AcrobatRect = Type.GetTypeFromCLSID(new System.Guid("{6D12C400-4E34-101B-9CA8-9240CE2738AE}"));
Acrobat.CAcroRect rect;
int x, y;
const int ZOOMFACTOR = 150;
Bitmap pdfBitmap = null;
string fname = "C:\\Inetpub\\wwwroot\\ASPApp\\PDF\\btmap" + numPg.ToString() + ".bmp";

try
{
  rect = (Acrobat.CAcroRect) Activator.CreateInstance(AcrobatRect);
Acrobat.CAcroPoint oPoint = (Acrobat.CAcroPoint)pdPage.GetSize();
y = oPoint.y*ZOOMFACTOR/100;
rect.Top = 0;
x = oPoint.x*ZOOMFACTOR/100;
rect.bottom = (short)y;
rect.Left = 0;
rect.right = (short)x;
pdPage.CopyToClipboard(rect,0,0,ZOOMFACTOR);
IDataObject clipboardData = Clipboard.GetDataObject();
pdfBitmap = (Bitmap)clipboardData.GetData(DataFormats.Bitmap);
pdfBitmap.Save(fname);
pdfBitmap.Dispose();
}
catch (Exception ex)
{
}
return fname;

---

The logic was to create bitmap file for each page and print these pages.
The above error I am getting is at the line:
pdfBitmap = (Bitmap)clipboardData.GetData(DataFormats.Bitmap);

Any help is appreciated