Extend Validity option is disabled in EG41

Hi Experts,

I did a Full device removal from an installation. Now i want to extend the validity of this device (like reversal).

My plan is to extend the meter validity(EG41) & then do a billing related Install(EG34).

So i first went to EG41, choose a valid time slice and then from the top menu select EDIT-->Extend Validity.

But this  option is greyed out. I remember doing this in another client location long back.

I want the device to be valid till 12/31/9999.

Can any one suggest me?

Thanks