diff --git a/blink_LED3.sh b/blink_LED3.sh
index af1826e..0ec7f27 100644
--- a/blink_LED3.sh
+++ b/blink_LED3.sh
@@ -19,5 +19,11 @@ echo "The LED3 user is starting"
 	sleep 0.5
 	echo "0" >> "$LED3_PATH/brightness"
 	sleep 0.5
+else 
+        echo "invalid parameter."
+        echo "To turn on the LED type: ./blink_LED3.sh on"
+        echo "To turn off the LED type: ./blink_LED3.sh off"
+        echo "To make the LED blink type: ./blink_LED3.sh blink"
+
  fi
  echo "Done"