Joining Date - Joining Letter

Hi,
I joined in my company on 11th May 2009 ,and stayed there for complete working hours.Then company asked us to come back on 18th May 2009.In that case what will be my joining date?
My offer letter clearly states that my joining date is 11th May.
Kindly reply.

Hi Sanoona,
It is obvious it will be 11 May 2009
Regards,
-Jyotshna

But unfortunately I doesn't have a hard copy of offer letter only soft copy I have .So my company is not accepting it.

Hi Sanoona,
Your DOJ would ideally be 11th May, but they might put you on Loss of Pay for the days you have not come to office i.e till 17th May. Check with your HR
Hard copy of offer letter is not required if the soft copy has been sent and has the digital signature of the authorized person.
Regards,
Sushma

I checked already.They are not accepting it. My manager is telling you should have told this that time ,after 4.10 years there is no point in telling all these things.Actually I was a fresher that time and I didn't know about the importance of this.So I didn't try to change the date.

There should be some evidence in your company that you reported on 11th May 2009 by way of signing of muster roll
or electronic attendance punching. Please unearth that evidence and discuss with your manager, alongwith this proof
and try to convince him/her that your date of reporting for duty is your DOJ.
Thanks
R K Nair