Hi vijay,
Your doing the settings correctly,but still your not getting the field in change mode.
This is because your doing the settings for some other screen layout.
please select the right screen layout(i.e)
In t.code OAOA you can see the details of asset class in which you will find screen layout for that related asset class(In the above case it is E070),please do the settings in the related screen layout to see the affect for that asset in the below mentioned path.
Path or Node: Financial Accounting (New) --> Asset Accounting --> Master Data --> Screen Layout --> Screen Layout --> Define Screen Layout for Asset Master Data.
As mentioned above screen select the related screen layout which you have seen in the above mentioned(T.code OAOA) like screen of yours.
Regards,
sanjeev.