Wait a little longer. It's late in the season and the tubers aren't gonna just jump up.

I just did a division on a canna here and for the first, time, here in JUNE, I got disappointed, because the transplant just wilted and flopped over. But after about a week of watering, it's finally starting to straighten up and look healthy. That kind of answers the question ... "Can I divide my Canna now, or should I wait till fall when they are dormant?" These are very hardy plants and although they may be prone to stress in summer months that might not favor instant propogation ( and I might add, gratification ) by division, they do turn around eventually.

I have however, had a couple rhizomes not grow and the reason, was clear before I planted them. As an experiment, I planted a few rhizome pieces that did not have buds or a growing leaf or leaf mass. True to what anyone will tell you, it won't grow.

If you have your receipt and are not satisfied, take them back to Walmart, before the ability to do so expires.

Try soaking WM & other inexpensive rhizomes before planting;

they may have been in those plastic body bags for a long time.

Horn Canna Farm is a good online source, & Calloway's here has a good selection.

This late in the year, you might do better to post on the Exchanges forum & ask for cannas for postage if you don't have some to share yet.