There's no problem for us if you post it here. However, this site is focused on SQL Server and you might not get the best answers. You should try an Oracle forum.
I'm not great at Oracle, but aren't you missing a table on MERGE statement?
Luis C.
General Disclaimer:
Are you seriously taking the advice and code from someone from the internet without testing it? Do you at least understand it? Or can it easily kill your server?
How to post data/code on a forum to get the best help: Option 1 / Option 2