This is how it works, same as if you were going into an RSP say from a TSFA. You are allowed to choose any price on the days range it was transfered. Going into an RSP you would probably want the highest number so the less capital gains can come off if/when you make any, IE you bought it at 16 not 15 that day and sold at 20. The other which is you case, you probably want the lowest number as you can take it as a loss of capital and write it off.

Edit: According to MoneyK maybe you can't count the loss, but that is how it worked for me going the opposite way before.