Thank you very much for all the sound advice.  To answer some questions, I was using a spore syringe, and the trash bag I used was black opaque.  I don't remember checking its transparency, but I may have used 2 bags just to be sure that no light was getting it.  It was a seed mix, but the sunflower seeds floated to the top when boiling/soaking, so I scooped them out.  Otherwise, I don't remember much about this because it happened at least 2 years ago.

Something I just remembered:

After I gave up on the jars, I put them on a shelf in the garage.  I planned on cleaning them out later.  I never got around to it, and after a few weeks, the jars were filled with green mold.  I guess something got in the jars from the air in the garage, but this might indicate that fungicide was not the problem.  Maybe it really was bad spores, as Enoon suggested.

So far, I've learned:

1. 80+ degrees is too warm for mycelium growth.

2. More than an hour in the PC can dry out the substrate.

3. Pure millet is better than mixed seeds.

4. I need to learn what gas exchange is (I presume it means that the inoculated jars should be able to breath)

5. The jars should be completely cooled before inoculation.

6. Darkness may not be necessary for mycelium growth (I'll shoot for it just in case).

Thanks for all the advice.  You have all been very helpful, and I'm sure I will succeed at this in the future (hopefully on my next attempt).