I am able to create the trigger for an insert to a local table
So, it could be the problem for the remote-database.
Did you try to create a procedure that is able to insert a record in cdcsample@dev.
And then call this procedure from the trigger.
create or replace trigger tr_cdc
after insert on cdcsample for each row
REFERENCING NEW AS NEW OLD AS OLD
insert into cdcsample@dev(a1,a2,a3,a4) values(:new.a1,:new.a2,:new.a3,:new.a4);