I'm sending how it was originally working 

A proxy was imported to the workspace with many attribute to use. datasheetdataservice is ourwebservice

Its created an instance and attribute, which I need "entrada" as entrance in xml and "resposta" as return to datawindow 

dataconnectiondstrequest entrada[]
dataconnectionsapresponse resposta[]

entrada[1] = create dataconnectiondstrequest
resposta[1] = create dataconnectionsapresponse

and code as 

datasheetdataservice lnv_webservice
SoapConnection conn

conn = create SoapConnection
conn.setbasicauthentication( 'confab', 'login', '*****')
ll_rc = conn.CreateInstance (lnv_webservice, 'datasheetdataservice')

And then after getting info from entrada

has a connection with one of attribute imported from datasheetdataservice webservice.

I'm having trouble to do that on REST, even I do instance, it only return -1, what do i need to change? How i use REST in this occasion

Thanks