I tried display the contents of a ztable and then I got the following message "No table entries found for specified key " and then I wentt to sm30 and tried to display the table there and found the followng message" The maintenance dialog for Ztable is incomplete or not defined" so can you please tell me what exactly the problem is and how do get rid of this. What I think is that the table is still not maintainable.
There are two issues in your question.
1) No table entries found- it means there are no entries in you table for th selection you ve provided in SE16 screen.
2)SM30- NO maintenance view exists for this table.
It means that a Table Maintenance view is not created for this table. You can ceate one from SE11.. by following the below navigation.
> Enter tablename>Display >Menu 'Utilities'>Table Maintenance generator. Give a Function group where you want the Tble maintennce programs needs to be created and Click on the Create icon.
Hope this helps!