Fix bug

app.py

@@ -344,8 +344,8 @@ def validate_key_and_model(key: str, model: str, api_base: str = None):
 
 # --- Wrapper for the grading function ---
 def run_grade(file_obj, key, model, api_base, progress=gr.Progress(track_tqdm=True)):
-    if model is None:
-        model = "gpt-4.1-mmvet"
+    if model == "gpt-4.1":
+        model = "gpt-4.1-mmvet" # in our Azure OpenAI base, the model name is gpt-4.1-mmvet
     if "mmvet" not in model:
         ok, msg = validate_key_and_model(key, model, api_base)
         if not ok: