diff --git a/data_processor.py b/data_processor.py
index 9628d92f..2c956e21 100644
--- a/data_processor.py
+++ b/data_processor.py
@@ -5341,7 +5341,7 @@ class DataProcessor:
             # Iteriere ueber das Mapping von internen zu COLUMN_MAP Schluesseln
             for internal_key, column_map_key in col_keys_mapping.items():
                 # Hole den tatsaechlichen Header-Namen aus dem Sheet
-                header_name_from_sheet = headers[COLUMN_MAP[column_map_key]]
+                header_name_from_sheet = headers[COLUMN_MAP[column_map_key]['index']]
                 # Fuege das Mapping hinzu
                 header_to_internal_key[header_name_from_sheet] = internal_key
                 # Fuege den Header-Namen zur Liste der auszuwaehlenden Spalten