I am trying to immigrate to my sons state but it says target zone too powerful can not migrate, what..

If you have already reached level 6 then you can only move state with the immigration option. But there are restrictions on which states you can move to. It sounds like you will not be able to move.

If you are still below level 6 (and have been playing for less than 2 weeks) then you can use the newbie teleport to move to any state. To do this simply move to the required state in the world map and tap anywhere to get an option to change state.

If you have not invested too much time in your current game then an option would be to abandon it and start a new game and move to the required state.