There are a couple of answers to this question. In order from most to least likely:
Search Errors:
Search errors are when an instructor searches for a student incorrectly. The ONLY effective way to search for a student is by his/her OneTech username. DO NOT search for a student by his/her last name or any other parameter except his/her username. At times, last names change, first names change, or many things will change; however, the OneTech username is the ONLY thing we can rely on, and it is 98% accurate. If you are still having difficulties finding a student, please contact the Course Management Systems Coordinator at tmanly@atu.edu or 479-964-0583 Ext. 1012.
The student is already in your course. When you navigate to the enrollment section in the Control Panel of your course shell, and type in the OneTech User ID of the student you would like to add, at times you will get 'no results'. That is because all the students are placed into a pool of 'available enrollees'. When a student is placed in your course shell, she/he is taken out of this pool. Blackboard is 'smart' and looks at your course shell. If a student is in your shell, then Blackboard takes the student out of this applicant pool knowing you cannot enroll the same student twice. If you find you cannot find a certain student, double check to see if she/he is already enrolled in your shell.
The Student Does not Exist:
At times, students enroll a bit late, and it will take some time to get them through the normal computer process, just like with any other organization. Recommended action is to just be patient. Once a student has enrolled, it should take about 3-4 days to get the student processed completely. If it has been longer than this, then you will want to contact the Campus Support Center at campussupport@atu.edu or 479-968-0646.