External classes 1120: Access of undefined property

I have a stage with three movieclips which are called: Mountain_mc, Sun_mc, Village_mc. There is no code in the .fla and it references to the main class.

I have a main class and three subclasses (for each movieclip one). I can acces the movieclips in the main class without a problem, but when I try to acces the same movieclips in the subclasses I get errors like: 1120: Access of undefined property Village_mc.

I have searched a lot to find the answer and I know it is not smart to acces the same mc in different classes but it would really be helpful to me. Can anyone help me or pinpoint me in the right direction?