Fields Missing in Transaction

In transaction ME23N(Display PO) I cant see the WBS element field when I select the Services tab.

In transaction ML81N, I am also missing a few fields (1 of them is also the WBS element tab).

This was not always the case. I used to be able to see these fields.

A user with the same GUI and patch level as mine does not have this problem. When I try to log on using a different workstation, I still have this problem. How do I rectify this?