diff --git a/src/entry/Maat_api.cpp b/src/entry/Maat_api.cpp
index 5cf746e..3a96137 100644
--- a/src/entry/Maat_api.cpp
+++ b/src/entry/Maat_api.cpp
@@ -209,10 +209,16 @@ int region_compile(_Maat_feather_t*feather, struct _INNER_scan_status_t *_mid, c
 		}
 	}
 
-	scan_ret=bool_matcher_match(bm, thread_num, 
+	if(bm)
+	{
+		scan_ret=bool_matcher_match(bm, thread_num, 
 								_mid->all_hit_group_array, _mid->all_hit_group_cnt,
 								(void **)relation_array, MAX_SCANNER_HIT_NUM);
-
+	}
+	else
+	{
+		scan_ret=0;
+	}
 	if(scan_ret>1)
 	{
 		qsort(relation_array, scan_ret, sizeof(struct Maat_compile_group_relation**),
diff --git a/src/entry/Maat_command.cpp b/src/entry/Maat_command.cpp
index 5b7bc7f..ebe9417 100644
--- a/src/entry/Maat_command.cpp
+++ b/src/entry/Maat_command.cpp
@@ -247,7 +247,7 @@ int invalidate_line(char* line, enum MAAT_TABLE_TYPE type,int valid_column_seq)
 void serialize_group(const struct Maat_group_t* p_group, enum MAAT_OPERATION op, char* buff, size_t sz)
 {
 	if(op==MAAT_OP_RENEW_TIMEOUT) op=MAAT_OP_ADD;
-	snprintf(buff, sz, "%d\t%d\t%d\t%d\t%d", p_group->group_id, 
+	snprintf(buff, sz, "%d\t%d\t%d\t%d\t%d\tnull", p_group->group_id, 
 									p_group->parent_id,
 									op,
 									p_group->not_flag,
diff --git a/src/entry/Maat_rule.cpp b/src/entry/Maat_rule.cpp
index b14a545..4fb6d79 100644
--- a/src/entry/Maat_rule.cpp
+++ b/src/entry/Maat_rule.cpp
@@ -619,6 +619,7 @@ void make_group_set(struct Maat_compile_group_relation* relation, struct bool_ex
 		{
 			continue;
 		}
+		//high 32 bit is virtual table id, low 32 bit is group id.
 		a_set->items[j].item_id=(unsigned long long)relation->virtual_table_id[j]<<32|group->group_id;
 		a_set->items[j].not_flag=relation->not_flag[j];
 		if(a_set->items[j].not_flag)