Camera fixed only at one point

I did all the process right according to the lecture, but my camera is staying in one position only. Whereas in the lecture the camera moves according to the tank position. So please help me in fixing this.

Could you show your Tank’s blueprint?

I have continued going on with lectures with that error only, so I don’t know what was there in tank blueprint that time.

Sorry I should have been more specific. I meant the viewport part of it.