Reg. Resignation Notice Period Agreement while on L1-B.

Hi

I was full-time employee of some company on L1-B and when resigned i was able to give 1 week of notice period.

Now before coming to company Onsite location (i.e. USA), I signed one company agreement which has lot of points in that.

Out of which one point states "4 weeks advance of resignation".

 

As i did not served the 4 weeks notice, my company did not provide Experience Letter to me.

 

So my question is:

 

- Does this Notice period agreement holds true ?

 

Thanks

Dipak