In your case, I think you have to talk about your background/the courses that you took in high school and the ones you liked best. If you did well in any of these courses, explain what spark your interest then connect it to business administration. Bare in mind that there are components of business administration so Maths - accounting etc. Something to show progress or interest. You can do the same for software development; probably you had a course in information technology etc…The purpose of visit definitely explains that the VO is not seeing any motivation or valid reason for your proposed study.
I think you might need further guidance. Send me your email address. I’ll contact you to provide a better response after seeing your documents.