Custom blocks to display for students in moodle

I have created a custom block in moodle. The block displays perfectly on admin and manager account. But it doesnt display on the student account. I have created db/access.php file. I have also created tests/generator_test.php (copied as same from online_user block by changing the key names ). The block is not visible in site admistrator/users/permission/define roles/ student and then clicking on edit. (Block: online users allow). The same is not showing for my block. Some one please help me with this. I want to display that block on students dashboard.