diff --git a/KernelLibrary/SysMon.cpp b/KernelLibrary/SysMon.cpp
index acbef44..3da8364 100644
--- a/KernelLibrary/SysMon.cpp
+++ b/KernelLibrary/SysMon.cpp
@@ -538,6 +538,10 @@ bool EnumObCallbackNotify(POBJECT_TYPE objectType,ULONG callbackListOffset,ObCal
 	POB_CALLBACK_ENTRY callbackEntry = nullptr;
 	ULONG count = 0;
 
+	if (callbackListOffset == -1) {
+		return false;
+	}
+
 	if (!objectType) {
 		return false;
 	}
@@ -576,7 +580,12 @@ LONG GetObCallbackCount(POBJECT_TYPE objectType, ULONG callbackListOffset) {
 		return count;
 	}
 
+	if (callbackListOffset == -1) {
+		return count;
+	}
+
 	callbackListHead = (PLIST_ENTRY)((PUCHAR)objectType + callbackListOffset);
+
 	nextEntry = callbackListHead->Flink;
 
 	while (nextEntry != callbackListHead) {
diff --git a/WinArk/KernelNotifyTable.cpp b/WinArk/KernelNotifyTable.cpp
index f112e85..c23f59e 100644
--- a/WinArk/KernelNotifyTable.cpp
+++ b/WinArk/KernelNotifyTable.cpp
@@ -387,7 +387,7 @@ LRESULT CKernelNotifyTable::OnRemove(WORD /*wNotifyCode*/, WORD /*wID*/, HWND /*
 	auto& p = m_Table.data.info[selected];
 
 	CString text;
-	text.Format(L"ÒƳý»Øµ÷£º%p?", p.Routine);
+	text.Format(L"Remove notify£º%p?", p.Routine);
 	if (AtlMessageBox(*this, (PCWSTR)text, IDS_TITLE, MB_ICONWARNING | MB_OKCANCEL | MB_DEFBUTTON2) == IDCANCEL)
 		return 0;
 
@@ -413,12 +413,20 @@ LRESULT CKernelNotifyTable::OnRemove(WORD /*wNotifyCode*/, WORD /*wID*/, HWND /*
 			data.Type = NotifyType::ProcessObjectNotify;
 			data.Address = p.Address;
 			data.Offset = SymbolHelper::GetKernelStructMemberOffset("_OBJECT_TYPE", "CallbackList");
+			if (data.Offset == -1) {
+				AtlMessageBox(*this, L"Please delete the ntoskrnl.pdb, then launch the WinArk again", IDS_TITLE, MB_ICONWARNING | MB_OK | MB_DEFBUTTON2);
+				return 0;
+			}
 			break;
 		case CallbackType::ThreadObPostOperationNotify:
 		case CallbackType::ThreadObPreOperationNotify:
 			data.Type = NotifyType::ThreadObjectNotify;
 			data.Address = p.Address;
 			data.Offset = SymbolHelper::GetKernelStructMemberOffset("_OBJECT_TYPE", "CallbackList");
+			if (data.Offset == -1) {
+				AtlMessageBox(*this, L"Please delete the ntoskrnl.pdb, then launch the WinArk again", IDS_TITLE, MB_ICONWARNING | MB_OK | MB_DEFBUTTON2);
+				return 0;
+			}
 			break;
 
 		case CallbackType::RegistryNotify: