Acceptable formats of themes and plugins are zip and tar (tar.gz). The file may have an extension of zip, tar, tar.gz. Other types of files are not supported. The default format is zip.

Archive must be have one root folder: themes or plugins. Other root folders will be ignored. Single theme or plugin files must be located in one folder which is a subfolder of the root folder. For example files of default theme must be located in themes/default/.
will be in themes / default.

If you created theme or plugin please submit it.