Using National Instruments USB-6259

I'm trying to re-write the function for NI USB-6259 data acquisition system using the session-based interface.

The old code looks like this:

function data = In_Out_DAQpad1(sig, fs, iRange)

ao = analogoutput('nidaq', 'Dev1');
ai = analoginput('nidaq', 'Dev1');

out_chan = addchannel(ao, 2);
in_chan = addchannel(ai, 2:2);

ai.SampleRate = fs;
ao.SampleRate = fs;

ai.TriggerType = 'Immediate';
ai.ExternalTriggerDriveLine = 'PFI0';
ao.TriggerType = 'HwDigital';
ao.HwDigitalTriggerSource = 'PFI0';
ao.TriggerCondition = 'PositiveEdge';

ao.Channel.OutputRange = [-5 5];
ao.Channel.UnitsRange = [-5 5];

ai.InputType = 'Differential';

set(ai.Channel, 'InputRange', [-iRange iRange]);

ai.SamplesPerTrigger = length(sig)+round(fs*0.1);

putdata(ao,sig)

start(ao);
start(ai);

wait(ao,1+ceil(length(sig)/fs));

data = getdata(ai);

delete(ao);
delete(ai);
clear ao

How would I re-write this as a session-based friendly script? Here's what I have so far...

function data=In_Out_DAQPad1(sig,fs,iRange)

s=daq.createSession('ni');
ao=addAnalogOutputChannel(s,'Dev1',2,'Voltage');
ai=addAnalogInputChannel(s,'Dev1',2,'Voltage');
s.rate=fs;
addTriggerConnection(s,'External','Dev1/PFI0','StartTrigger');
ch=addAnalogInputChannel(s,'Dev1',1,'Voltage');
ch.Range=[-5 5];
ai.InputType='Differential';
set(ai.Channel,'InputRange',[-iRange iRange]);
ai.SamplesPerTrigger=length(sig)+round(fs*0.1);
putdata(ao,sig)

startForeground(s);
wait(ao,1+ceil(length(sig)/fs));
data=getdata(ai);

delete(ao);
delete(ai);
clear ao

When I try and execute this, I get the error No public property rate exists for class daq.ni.Session.

As you can tell, I'm very new to all this so any help would be greatly obliged.

Many thanks in advance.