Sometimes prints

I have the following code:
  */The printer has been initialized before with Begindoc;
Logo:=TBitmap.Create;
    WaData.Provider.Locate('Code',PrintMaskEdit1.text,[]);
    Logo.Assign(WaData.ProviderPicture);
    FitBit.Top:=round(0.125*DOTPI);
    FitBit.Left:=round(5.5*DOTPI);
    FitBit.Right:=round(8*DOTPI);
    FitBit.Bottom:=Round(1.5*DOTPI);
    Canvas.StretchDraw(FitBit,Logo);
    Logo.Free;

*/sometimes the Logo is printed and sometime not
*/ what is causing the sometimes printing?

Thanks

Alberto.