Primary Key Null values issue

Hi All,

I searched on SCN for this issue but couldn't get any solution,

I have created a custom table in ECC. I want Null values for some primary keys and for others I don't want any NULL values.

I tried removing check box for 'initial Values' column for which I don't want to allows user to save Null values.

It didn't show any error/warning during syntax check.

However, when I activated the Table, all fields are marked in 'initial Values' column.

I am not sure why SAP is overwriting my choice while activating the table that too without any message.

Can anybody help me with this.

Thanks.