I can't to expose the option sort Post Date in a view in Drupal 7 I have created a view type content, with the follow features:

Format

Format: Unformatted list | Settings

Show: Content | Teaser

Fields

The selected style or row format does not utilize fields.

Filter criteria

Content: Type (= article)

Content: Published (Yes)

Sort criteria

Content: Post date (desc)

When I checked the option "Expose this sort to visitors, to allow them to change it " in Sort Criteria>Post Date and press Apply, the sort Expose doesn't show and when I am going again to Post Date I can see that the change was not stored, the "Expose this sort to visitors, to allow them to change it" appears unabled.

What's my error?

Thanks for your help.
It seems to be an issue with having the devel module enabled.  If you are using it try disabling it and it should work.