Exception: Attempting to get unset feature: Duration

Hello,I want to get the 'estimate' and 'CorrectedEstimate',but it is always throw the exception."java.lang.IllegalStateException: Attempting to get unset feature: Duration"


listAll = getAll.testTotal("testReport002");



for(int i=0;i<listAll.size();i++){

IWorkItem wiAll=(IWorkItem) listAll.get(i);
System.out.println( wiAll.getDuration());

try{

IItem item2 = wiAll.getFullState();
if (item instanceof WorkItemImpl) {
WorkItemImpl wii = (WorkItemImpl) item2;

long corrected = wii.getCorrectedEstimate();
long corrected2 = wii.getTimeSpent();
//or wii.getTimeSpent();



thanks for help