Is it possible to add User Defined fields in the addrequest method of the API?

 

I'm trying to add a request using this url

http://incidencias/servlets/RequestServlet?operation=AddRequest&username=user&password=xxxx&logonDomainName=&DOMAIN_NAME=REPARALIA&category=pruebas&subcategory=pruebas&UDF_CHAR2=texto

 

the request is added but the Subcategoy andUDF_CHAR2 remain empty

thanks in advance