Company code/Purchasing Unit are not editable while creating PR

Hi,

Previously, while creating a PR, system pops-up to fill up company code and Purchasing unit fills up automatically once company code is chosen.Now, everything else is same only these two fields are not editable while creating new PR. Even if I copy old PR to create a new one, it does not allow to change the value.

Can anyone help me this.

Thanks,

Prakriti