Talk:What to do if installation of a signed MIDlet fails
From Nokia Developer Wiki
This simple article highlights several simple, but common problems that may lead to problems installing a signed Java ME midlet. Midlet signing can be very confusing for beginners, and the reason for the errors can often be difficult to track down. Almost every day, new threads are to be found in the discussion forums relating to problems installing signed Midlets. Some of the most common and confusing problems relate to a failure to list the required API permissions in the JAD file. Renaming a Midlet (and resulting inconsistency between the Midlet name and what appears in the JAD file) is another common cause of troubles.
The following link provides a useful discussion of midlet signing and common problems encountered: Midlet signing