How to fetch table data and show in a a!dropDown control of interface.

you have an error message at the left side ;)
 the paginginfo is missing at your a!query function. -> won't work without

I am getting an error even after using Paginginfo.

delete line 2 ;) 

Per what the error message says: in a!localVariables you can't just define a local variable and then nothing else.  You need some code to actually be executed after all local variable definitions are complete.  If you want to test out what the value of the local variable will be, you can simply put your local variable in as the "code to execute" section of the a!localVariables() call, and the value will be displayed.

Also: there's really no need to cast() the query results to the specified type (though you can if you really want to).  Usually it's not really worth the extra hassle, in my experience.

Per what the error message says: in a!localVariables you can't just define a local variable and then nothing else.  You need some code to actually be executed after all local variable definitions are complete.  If you want to test out what the value of the local variable will be, you can simply put your local variable in as the "code to execute" section of the a!localVariables() call, and the value will be displayed.

Also: there's really no need to cast() the query results to the specified type (though you can if you really want to).  Usually it's not really worth the extra hassle, in my experience.