Delphi 4 error:- Incompatible Types : “TBitmap” and “TObject”

Getting this error while I am trying to run /compile/build a Proiject

       Incompatible Types : “TBitmap” and “TObject”

The cursor is pointing to Bitmap := FSectionList.BackgroundBitmap

Kindly help me figure it out.
Struck here like a ambulance in heavy traffic

Here is the part of the code:-

procedure ThtmlViewer.DoBackground1(ACanvas: TCanvas; ATop, AWidth, AHeight, FullHeight: integer);
var
  ARect: TRect;
  Bitmap, Mask: TBitmap;
  PRec: PtPositionRec;
  BW, BH, X, Y, X2, Y2, IW, IH, XOff, YOff: integer;
  Fixed: boolean;

begin
ARect := Rect(0, 0, AWidth, AHeight);
Bitmap := FSectionList.BackgroundBitmap;    
if FSectionList.ShowImages and Assigned(Bitmap) then
  begin
  Mask := FSectionList.BackgroundMask;
  BW := Bitmap.Width;
  BH := Bitmap.Height;
  PRec := FSectionList.BackgroundPRec;
  Fixed := PRec[1].Fixed;
  if Fixed then
    begin  {fixed background}
    XOff := 0;
    YOff := 0;
    IW := AWidth;
    IH := AHeight;
    end
  else
    begin   {scrolling background}
    XOff := 0;
    YOff := ATop;
    IW := AWidth;
    IH := FullHeight;
    end;
  CalcBckgrndLoctionAndTilng(PRec, ARect, XOff, YOff, IW, IH, BW, BH, X, Y, X2, Y2);

  DrwBckgrnd(ACanvas, ARect, X, Y, X2, Y2, Bitmap, Mask, BW, BH, PaintPanel.Color);
  end
else
  begin  {no background image, show color only}
  DrwBckgrnd(ACanvas, ARect, 0,0,0,0, Nil, Nil, 0, 0, PaintPanel.Color);
  end;
end;

Thanks and Regards
Vas