take note ive also inserted additional column in the table  elgg entity user but still the custom field in the registration doesnt save in the database.

@caragadatacenter - First, read this: http://docs.elgg.org/wiki/Should_I_edit_the_database_manually%3F, especially the 2nd point. You should not add custom fields to any tables in Elgg. One of many reasons is because Elgg core won't know about the new fields, so will never save any information to them.

Also, do not edit core files. You need to pull your changes out into plugins so you can upgrade easily.

I think I got it , think you very much！