SQL & PL/SQL

I am using ORACLE 11g and my IED is SQL Developer 4.1.1

This is all the free PC version which has some limits.

I tried following:

CREATE TABLE hf_altertest 

( 

contact_id   INTEGER NOT NULL 

,first_name   VARCHAR(25) 

,last_name    VARCHAR(35) 

,PRIMARY KEY (contact_id) 

);

ALTER TABLE hf_altertest ADD COLUMN state CHAR(2);

But when I go to run the ALTER TABLE then I get following error:

rror starting at line : 1,323 in command -

ALTER TABLE hf_altertest ADD COLUMN state CHAR(2)

Error report -

SQL Error: ORA-00904: : invalid identifier

00904. 00000 -  "%s: invalid identifier"

*Cause:   

*Action:

I can run the very same code in MySQL with no errors.

That leads me to believe that maybe I am just bumping up against a limit in the free PC version.

Any thoughts?