SQL & PL/SQL

I have a trigger inside a .sql script like this

CREATE OR REPLACE TRIGGER "my_schema"."trigger_name" 
BEFORE INSERT ON my_table
FOR EACH ROW

DECLARE
            ........
BEGIN
            ........
END trigger_name;
ALTER TRIGGER "my_schema"."trigger_name" ENABLE;
/

I executed it with the command

@my_sql_script_name.sql

It said

Warning: Trigger created with compilation errors.

I then entered

show errors trigger <trigger_name>;

Now it says

27/1     PLS-00103: Encountered the symbol "ALTER"

What does it mean? I used that ALTER TRIGGER command to enable my trigger inside the sql script. How can solve this problem, Anyone please?