Object reference not set to an instance of an object

Has anyone ran into the problem "Object reference not set to an instance of an object" with the "results" object that is returned from the call to any NS action?
Ex:

//Declare an instance of the Write Reponse object
ns_ws.WriteResponse results;

//If there Customer ID is set, then perform an Update Action
// Else perform and Add Action
if (customerRec.NS_Internal_ID != null)
{
    //Make the call for the update
    results = _services.update(custAcct);
}
else
{
    //Make the call for the add
    results = _services.add(custAcct);
}

//Check for an error
if (!results.status.isSuccess)
{
   //format error message
   _err_msg += _displayEx.processStatusDetails(results.status);