Need to click on enroll to offering, even after enrolling to course

Summary:

Hi All,

Could be a basic thing.I have created a course and created offering for it.When employee enrolls into course.He is getting erolled, but after clicking on enroll, it is asking to select the offering.There is only one offering to this course.My question is why the employee has to enroll again to offering.If there are multiole offering s it fine.But when only offering why should he eroll again.Could you pls suggest if we need to make any specific setup, so when employee enrolls to course ,he doesnt have to select offering again.