sql statement ERROR please help......

Hi all,

I am using Oracle8i Enterprise Edition in window 2000

my problem as following

SQL> create table ttt
  2 ( name varchar2(100)
  3 ,
  4 constraint e check (name = lower(name)));

Table created.

SQL> alter table ttt
  2 modify constraint e
  3 check (name = upper(name));
check (name = upper(name))
*
ERROR at line 3:
ORA-00933: SQL command not properly ended  

How can I modify constraint e ????

                                  thanks.