you haven't create any instance of
objPastel
,
objPastel = new Lib.cPastel();
objPastel.CreateGRV(648337);
if you creating this instance of
cPastel
somewhere else in your program and asigning to
objPastel
, then you better check for null like below
if(objPastel!=null)
{
objPastel.CreateGRV(648337);
}