Below code gives null pointer exception even if VO has row and values

OAViewObject MyReqsGlanceVO =  (OAViewObject)am.findViewObject("MyReqsGlanceVO");   
if(MyReqsGlanceVO != null){

       String rowReference = pageContext.getParameter(OAWebBeanConstants.EVENT_SOURCE_ROW_REFERENCE);        


       OARow currRow = (OARow)am.findRowByRef(rowReference);  
             strSupplierSite = (String)currRow.getAttribute("SupplierSite");              

             Number number = (Number)currRow.getAttribute("RequisitionHeaderId");

             strReqHeaderId = number.toString();