allowed types in upload file

I have allowed types of dwg in my allowed_types, but why it doesn't work, while I have describe this extension in mimes.php. Anyone can solve this problem ?.

Or, is there another way to set disallowed types of file rather than to type very much of allowed types of file if we want to upload more types of data ??

Post your definition for DWG that you created in mimes.php, including the associated mime type definitions you used.