Are you receiving input correctly in receive input activity?
I am curious on the "Used by Rest Adapter (I converted my Json to XML, then, generate a xsd from XML)" statement.
What version of SOA Suite 12c you are using? If it is 12.1.3 the XSD will be automatically created for you after you finish the REST adapter wizard. In 12.2 you have the option to pick either pure REST JSON services which are handled with Java Script (as opposed to XSLT) or use traditional WSLD based ones.
Still double check what RakeshKr has advised.