SELECT NEXTVALUE FROM v$sequences

Hi Guys,

Do you know why after the database shutdown and startup if I run the following sql for an existing sequence, it ruturns NULL

  SELECT NEXTVALUE FROM v$sequences WHERE SEQUENCE_NAME='SEQUENCE_NAME';

But if I run first "select SEQUENCE_NAME.nextval from dual;" and then run the above  it ruturns correct value.

Thanks for your help,

Majid

PS- The sequence has been created with CASH option.