Why does this transaction give me an error?
The transaction wasn't going through because of the newly implemented "dust transaction" policy that makes it so that no output of a transaction may total less than 54.3 micro-bitcoins. One of my outputs was below this threshold. So I fixed that, but then the output to the "change" address was pulled below 54.3 uBTC and it still failed. I haven't found a way to ensure electrum doesn't try to deposit less than 54.3 uBTC into the change address, so for now I'm sticking with a single, large input to avoid small amounts of change.