Webservice send JSON without doble-quote("")

[Anonymous]

I have a simple webservice where I send the result from a mssql query through a webservice:

tMMSQLlinput-->tXMLmap-->tRESTtresponse

Problem is that I am sending a string through the webservice and the JSON field doesn't always have the doble-quote(""). This is the best picture to show the error:

I have to say that "quantitat" is a numeric field(talend bigdecimal) at the database but I have done all the possible casts to make it a string and still doesn't work.

This is my tXMLmap:

Any Ideas? I have checked all the schemas and stuff. Weirdest thing is that sometimes I am getting " " and sometimes doesn't. 

I have been working on it all the day but I am not being able to fix it.  I would appreciate any idea because I am not sure if this is a txmlmap problem, json...database with bigdecimal,deploying at karaf....I am lost.