Unable to see F4 help for Domain fixed values when displaying the table data

Hi,

I have a Z table where i have created a new field in it. In Domain i have maintained Value range (single vals) (seen from the attached screen shot S1.jpg). But when i display the data, for this field i'm unable see the F4 help (unable to see the dropdown, seen from the attached screen shot S2.jpg).

What could be the reason here?

Thanks,

Sk