Possibly due to the fact there is no relevance to your qualification and permits are granted on the basis that a student is building on current qualifications/work experience and not heading for a different career path. Do you have any work experience in that area ?
All you can do is apply with a good explanation of why you need to come to Canada for a course in a different direction to your qualifications/work experience, how this will improve your prospects when you return home and hope for the best.
