Finally!

Good news: I finally got a PCR product to work! It seems that the annealing temperature was indeed the problem behind my previous failed PCRs.

However, I have found another oddity. It seems that only some of the primers worked. I had been using two different pairs of primers to cut the genomic DNA at different sites and obtain different fragments. Even though the one pair did not work, my results are consistient. Since all samples of the first primer pair worked, and none of the second pair worked, I can safely conclude that the problem has to do with the DNA-primer interaction, and is not a mistake made on my part.

I will be further investigating this anomaly prior to sending in the DNA fragments to be sequenced.