diff --git a/devlib/utils/parse_aep.py b/devlib/utils/parse_aep.py
index 357ba4b..dd0ac00 100755
--- a/devlib/utils/parse_aep.py
+++ b/devlib/utils/parse_aep.py
@@ -343,7 +343,7 @@ class AepParser(object):
 
             # get 1st time stamp
             if begin <= 0:
-                being = data[0]
+                begin = data[0]
 
             # skip data before start
             if (data[0]-begin) < start: