i add the lock in activity plugin and i notice that i cant lock quizport activity only...
I'm sorry I don't fully understand.
Can you show me a page in the Moodle docs which describes the Activity Locking plugin that you are talking about?
If your aim is to prevent access to a QuizPort until a student reaches a certain grade on another activity, then you should edit the QuizPort activity, and select a "Previous activity" and grade.
I haven't used the Activity Locking system myself, so I can't say for sure why it does not behave the way you want it to behave. Furthermore, I am rather too busy at the moment to investigate this myself. Maybe the maintainers of the Activity Locking system would be willing to add QuizPort to the list of activities it knows about?
In the Moodle coures that I use, I implement this kind of activity locking using QuizPort's "Previous activity" and "Next activity".