Problem Transfering Music

Hello, When i try to drag music to my ipod in itunes it doesnt work nothing happens. It works on my labtop but im trying to get it to work on my desktop. I already set it to transfer songs manualy..How can i get it so i can just drag songs again? and I think this is becuase its a different pc? thanks.

 

You didnt read what i said i did that already i did all the obvious things but still wont work I think its becuase its a different computer but how do i fix it