SQLFiddle no output

When i build the following schema:

 CREATE TABLE CUSTOMER(
  CUSTOMER_ID INT NOT NULL,
  PRIMARY KEY(CUSTOMER_ID)
);

INSERT INTO CUSTOMER(CUSTOMER_ID) VALUES(1);

and run the following query:

SELECT CUSTOMER_ID FROM CUSTOMER;

I get no output. Can somebody please explain to me what is wrong?

it works just fine. see here sometimes sql fiddle stops functioning or shows loading error due to server load; perhaps that's why.