can't export my xml file from wordpress

I'm trying to download my xml file using the worpdress tool > export but seem like i can't and prompt me a firerfox error saying

Quote:

---

Firefox can't find the file at http://domain.com/wp-admin/export.ph...ad+Export+File.

---

what could be the wrong thing here?

It looks like you have a missing or corrupted export.php file.

Check the wp-admin directory to see if the file is there. If it is, copy a new version to the directory.

If you have not done a recent WordPress update, try doing an update. It may replace the file if it is corrupted.