fix wb rebuild bug

@@ -54,7 +54,7 @@ class BSWorkbook(Workbook):
             # TODO 关键字段再次查找
             if header_idx is None:
                 continue
-            letter = get_column_letter(header_idx)
+            letter = get_column_letter(col)
             ws.move_range("{0}1:{0}{1}".format(letter, ws.max_row), cols=header_idx - col)
         ws.delete_cols(self.fixed_col_amount + 1, amount=ws.max_column)
 
@@ -147,8 +147,9 @@ class BSWorkbook(Workbook):
 
     def build_month_sheet(self, role, month_mapping, ms):
         tmp_ws = self.create_sheet('tmp_ws')
-        for month, parts in month_mapping.items():
+        for month in sorted(month_mapping.keys()):
             # 3.1.拷贝数据
+            parts = month_mapping.get(month)
             new_ws = self.create_sheet('{0}({1})'.format(month, role))
             new_ws.append(self.fixed_headers)
             for part in parts: