Regular expression help required please

From what I understand the sql below should return 'Hello World', however it actually returns 'HelloWorld' i.e. the whitespace is not ignored.

Can anyone tell me what I am doing wrong?

Thanks

SELECT regexp_replace('H\/e l£lo World','[^a-zA-Z0-9]', '') FROM dual; Received on Tue Sep 21 2010 - 06:31:08 CDT