When an employee does not show up in a dropdown, usually, the emloyee does not have rights to the area for the customer. To give them rights to that area, go to your HR > Lookup Employeepage, find the employee, and click on their name to access their employee account. Click on the Areas button at the bottom. Check the box next to the area you would like him/her to have rights for. Update, log out, and log back in to view the changes.