I do understand what you want. I don't understand why the formula you are using doesn't work, or how it doesn't work. Can you please tell me what results you get from that formula?
For example, if I use that fomula in an expression box on a form, I get the result:
daily status report - 2008-12-04
Now, I don't know off hand if a '-' is allowed in a file name on SharePoint. You may want to test by trying using a static file name with a '-' in it. If it isn't, you'll want to use the translate function to remove the '-' from today.
concat("Status report ", translate(today(), "-", ""))
for example. I hope that helps....