RAISE EXCEPTION not working

I am trying the use the following statements in a function:

            SELECT INTO temp_i id FROM public.t_customer_profile WHERE

                                    id=cust_id;

                  IF NOT FOUND THEN

                        RAISE EXCEPTION "Username already exists";

                  END IF;    

I know the table and the select statement is correct.

And I keep receiving the following error:

WARNING:  plpgsql: ERROR during compile of f_insert_login_profile_record near line 19

ERROR:  syntax error at or near ""Username already exists""

I do not understand why.

Thank you.

Brian H Mayo

bmayo@comcast.net