Dilaudid is not effective for my pain, but weaker opioids are, is this true?

It could be: All semisynthetic opiates like hydromorphone (dilaudid) actually are broken down into Codeine and morphine, and it is the morphine that actually works. Some people lack the enzymes that break down the drug, so that it isn't turned into codeine, or Codeine isn't turned into morphine. You may have the enzymes that permit other semi-synthetics to be metabolized. This is common with Codeine in kids.