ORA-01861: literal does not match format string

I'm pretty sure this is something really silly.

Instead of spending another 10 minutes with this ( or better said, while I spend another 10 minutes with this ) I'll ask it here in parallel.

What's wrong with the following statement:

select to_date( '30/10/2009 18:27:35', 'DD/MM/YYY HH24:MI:SS'开发者_Go百科) from dual

The error message is:

Error: ORA-01861: literal does not match format string

SQLState:  22008
ErrorCode: 1861
Position: 0

'DD/MM/YYY HH24:MI:SS'

Try this with four Y's

'DD/MM/YYYY HH24:MI:SS'