ADID Field is not editable in contract Account screen

Dear Expert,

I want to create a new contract account  , while creating contract account through T-Code  CAA1 , Account Determination ID field is populating as not editable.

Earlier it was ok and contract account was created successfully but I am not able to find out what went wrong and now I am not able to enter ADID in contract account screen . Due to this I am not able to create contract account.

Could you please help me on this. I have checked with basis team and they have assigned  SAP_All access to my ID.

Please find the corresponding screenshot attached herewith. Any help on this will be appreciated .

.

Thanks & regards,

Gyanendra