Strange.
You could do following:
1. Delete all com_uddeim folders (in administrator/components/ and components/) and delete all uddeim entries in Joomla tables. Then install the correct package for your Joomla version and you will find uddeIM in the extension manager).
OR
2. Unpack uddeIM package and upload and overwrite all files (except the config file) on your server.
uddeIM & uddePF Development
CB Language Workgroup
CB 3rd Party Developer