I looked at the display and the box for a Cosco Apex at Babies R Us and I was surprised that this issue with the seat-back is not made clear somehow before the purchase is made. I'm assuming the user manual states somewhere that the Apex is not to be used with a lower-backed seat, but how many parents actually read that thoroughly? And why should it be a secret until after you've purchased the product and taken it home? I'm really aggravated that this product which is intended to be a safety device can be so easily and innocently mis-used so as not to provide the safety it is supposed to. Makes me really not want to buy anything made by Cosco. Who knows what else they are skimping on?