diff --git a/khaosz/core/transformer.py b/khaosz/core/transformer.py
index ae2d9c3..3ec47f3 100644
--- a/khaosz/core/transformer.py
+++ b/khaosz/core/transformer.py
@@ -99,6 +99,8 @@ def process_attention_mask(
         return None
     
     if seq_mask.dim() > 2:
+        # shape (bsz, seq_len) or (bsz,n_heads, seq_len, seq_len + start_pos)
+        # if ndim > 2, it's 4D tensor
         return seq_mask
     
     batch_size = seq_mask.size(0)
diff --git a/khaosz/trainer/dataset.py b/khaosz/trainer/dataset.py
index 7dcd326..908447e 100644
--- a/khaosz/trainer/dataset.py
+++ b/khaosz/trainer/dataset.py
@@ -48,7 +48,8 @@ def build_attention_mask(input_ids: Tensor, user_token_id: int, multi_turn: bool
     iq = turn_id.view(seq_len, 1)
     ik = turn_id.view(1, seq_len)
     
-    seq_mask = (iq <= ik) if multi_turn else (iq == ik)
+    # fix the causual attention mask
+    seq_mask = (iq >= ik) if multi_turn else (iq == ik)
     causal_mask = torch.tril(torch.ones(seq_len, seq_len, device=input_ids.device)).bool()
     attention_mask = seq_mask & causal_mask
     
diff --git a/khaosz/trainer/strategy.py b/khaosz/trainer/strategy.py
index 7f1f7e8..e94b122 100644
--- a/khaosz/trainer/strategy.py
+++ b/khaosz/trainer/strategy.py
@@ -159,8 +159,17 @@ class StrategyFactory:
     def load(model, train_type, **kwargs):
         train_strategy: Dict[str, Callable[[], BaseStrategy]] = {
             "seq": lambda: SeqStrategy(model),
-            "sft": lambda: SftStrategy(model, kwargs.pop("bos_token_id"), kwargs.pop("eos_token_id"), kwargs.pop("multi_turn")),
-            "dpo": lambda: DpoStrategy(model, kwargs.pop("pad_token_id") , kwargs.pop("dpo_beta"))
+            "sft": lambda: SftStrategy(
+                model, 
+                kwargs.get("bos_token_id"), 
+                kwargs.get("eos_token_id"), 
+                kwargs.get("multi_turn")
+            ),
+            "dpo": lambda: DpoStrategy(
+                model, 
+                kwargs.get("pad_token_id"), 
+                kwargs.get("dpo_beta")
+            )
         }
         strategy = train_strategy[train_type]()
         return strategy