Hello mikenz,
You may have to pay tax installments towards your 2014 tax balance because your taxes owing in 2014 (estimated) and in 2012 or 2013 is more than $3,000, respectively. Also, you may have not made your March 15, 2014 installment payment (which is the due date for the first payment) which is why the CRA allocated it there appropriately.
For more information, check out the pamphlet: http://www.cra-arc.gc.ca/E/pub/tg/p110/p110-e.html#whydoyouhavetopaytaxbyinst
Please note that failure to make the installment payments by their due date may result in interest.
Madan Chartered Accountant team
www.madanca.com