diff --git a/justfile b/justfile
index 1ccd971..465271e 100644
--- a/justfile
+++ b/justfile
@@ -20,7 +20,9 @@ pythonlib:
 trainbot:
   #python ./store/python/trainModel.py
   # cargo run --bin=train_dqn # ok
-  cargo run --bin=train_dqn_burn
+  cargo build --release --bin=train_dqn_burn
+  LD_LIBRARY_PATH=./target/release  ./target/release/train_dqn_burn
+  # cargo run --bin=train_dqn_burn # utilise debug (why ?)
 debugtrainbot:
   cargo build --bin=train_dqn_burn
   RUST_BACKTRACE=1 LD_LIBRARY_PATH=./target/debug  ./target/debug/train_dqn_burn
diff --git a/store/src/board.rs b/store/src/board.rs
index ada22c9..646e929 100644
--- a/store/src/board.rs
+++ b/store/src/board.rs
@@ -564,6 +564,7 @@ impl Board {
         }
         let checker_color = self.get_checkers_color(field)?;
         if Some(color) != checker_color {
+            println!("field invalid : {:?}, {:?}, {:?}", color, field, self);
             return Err(Error::FieldInvalid);
         }
         let unit = match color {