I presume, that you did not wait, until SPONTANEOUS new growth from the bulbs would show up. And, what is or concisely had been the temperatures that you had stored your bulbs with?

You are correct; I did not wait for new growth before potting them up. The area of the basement where I stored the bulbs is probably 68 during the day and 60 at night.

68F eq 20C is already to high
[Read F as degree Fahrenheit and C as degree Celsius respectively]
The preferable range for storage is
50F eq 10C to
63F eq 17C
Perfect, for the elongation of the preformed scapes within the bulbs, with max speed is
55F eq 13C

Contrary to popular belief, the refrigerator
41F eq 5C
is not the appropriate location for the storage of your bulbs, after you "harvested" them. It is but a good means to DELAY any growth, namely out of bulbs that HAD already been pretreated (stored at approx. 55F) for example such bulbs that you have just purchased.

My temps in the basement are pretty much perfect then, and yet I still have a small army of unblooming bulbs :(

But on the plus side, as I have learned more and more since I first became addicted in 2004, the bulbs from 2004-2006 pretty much shrivelled away to nothing, as I really did not do anything to make sure they thrived; 2007-2008 - bulbs began going outside in the summer and stayed a little larger, but still no blooms, maybe one; 2008-2009 - bulbs are receiving all the prescribed care, and are large, firm healthy looking, and I actually had 2 reblooms last year. That may not sound like much, but it was a small victory for me :)

So - each year, I have some improvement, but sadly few reblooms, hence the purchasing of new bulbs annually, and the expansion of the "army":) In my climate, and home/dormant conditions, I don't know what else I can do.

From someone who grows them outdoors in the ground: more sun. Don't have to have full sun, all day - although that will work. But not full shade either. Mine need some sun to bloom. The ones that do best are in part sun/part shade or filtered/dappled light. Light not only makes then bloom but also makes the bulb and leaves stronger. Blooms grown in weak light (such as indoor or window lighting) are weak plants. These are outdoor plants in their native, natural setting.

i live in dallas texas area. some of my bulbs are stored in the unheated garage for the winter. as soon as i see bits of new growth popping out, i move them outdoors. i dont want to wait too long, so that the new growth is not burned when placed into the light. i only carry them back inside when frost threatens.
good light is essential, not only to provide energy for the plants growth, blooming, metabolic processes, but there also has to be enough extra energy or food to be stored into the bulb, to keep it growing. i have amaryllis in pots in full sun in the greenhouse thru mid-march, then light shade until mid-october.