hi,, i got rejected for the same reason in my first attempt and got through in my second.
dont lose hope and its very easy to get a visa in the second attempt for such a reason. all i did was get a support letter from college in canada stating the course relevance and on what basis iv got admission and a bonafide from my college in india . also make a VERY STRONG sop stating why u wanna pursue ur course and what makes u genuine student and ur plans after the course, do mention u intend on coming back to ur home country..
Hope this helps and all the best...