Where is my signature? I signed a petition but cannot find my signature listed.

You may have signed the petition as "Anonymous". In this situation you will not be able to search your name in the signature list. If you have been sent a signature receipt by email, then your signature will exist except if deleted by the author. If you have, or obtain, a verified GoPetition account, then you can log in and click on "My personal signatures" to view your signature(s). 

It is also possible that your signature exists but you are viewing a cached (old) version of the signature list in your browser. If you clear your cache you may then be able to see your signature. Moreover, if you receive a signature receipt, then you have definitely signed the petition.