When I try to conect to Zimbra Server via Soap allways say not authorized.

I get the AuthToken like this:
String tok = sp.getAuthToken();
sp is the class SoapProvisioning in package com.zimbra.cs.account.soap.SoapProvisioning

and I build the URL https://server/service/preauth?isredirect=1&authtoken={} and between the branches token value.
And allways opens Zimbras login screen.
Before doing all this I autenticate as admin and reponse was correct.

Anyone tried a Signal Sign On with Zimbra?

Thank you