Doesn't Work With WP 3.7.1

Hi everybody, sorry if I write wrong, I’m a developer from Brazil and my English is kind of lame lol!
So i’ve beem trying to get some custom field of dropdown type and i create the field and use the echo get(name_of_the_field), but the content doesn’t appears, so i note that in admin of the post the value is getting empty when a click update or post! Anybody could help me please! I’m getting angry with that. I have another site whith the same config and this bug isn’t happening!!! I don’t know what can I do to fix this prob!

I noted too, that the same occour when i need to update the configs of plugin, not only into post but the config of anything, like groups and fields, and the checkboxes inside the configuration. But i can create a fields, and everuthing.

THX a lot guys!!!

PS: when I update the URL goes to taht message:
post.php?post=27&action=edit&message=1

http://wordpress.org/plugins/magic-fields-2/