I want to do a simple PL/SQL program on the Oracle 10g internet environment. The program is:

DECLARE
stud_rec students%ROWTYPE;
last_name VARCHAR2:='Clinton';

BEGIN
    SELECT * INTO stud_rec FROM students WHERE student_id=100;
END;

I have a table called students with data inside of it. The issue is that when I want to run this in the SQL command window I got this message:

  ORA-06550: line 3, column 11:
  PLS-00215: String length constraints must be in range (1 .. 32767)

I have checked the syntax and I cannot find the error. Any help? Thanks in advance