Update data connection WSDL dynamically

Hi Community - Sorry, this question has been asked before but I can't get it to work and I can't figure out what I am missing. 

I've been given a WSDL file for a webservice, which I have imported into my form.  I found on the forums/google how to update the connection for different environments (e.g. DEV/TEST/Prod) but I can't get it to work.

I created a custom button, with control type = regular and put the following java into the click event:

var cUrl = $record.WEB_SERVICE_URL.value;      //Dynamically assign WSDL Definition URL

var service = SOAP.connect(cUrl);

xfa.connectionSet.SAP_PI.execute(0);

Gives me the following error:

NotAllowedError: Security settings prevent access to this property or method.

SOAP.connect:5:XFA:data[0]:Page1[0]:PageHead[0]:Submit[0]:click

I've also tried replacing the second line with "xfa.connectionSet.SAP_PI.soapAddress = cUrl;", but I get a similar error:

GeneralError: Operation failed.

XFAObject.soapAddress:6:XFA:data[0]:Page1[0]:PageHead[0]:Submit[0]:click

Property: 'soapAddress' cannot be set because doing so would violate this document's permissions settings.

I am using LC ES3 and testing the forms on Adobe Reader XI.

Any help and/or example documents greatly appreciated.