Use the Assistant ID, not the name. Even if the name looks right, the system usually wants the actual ID (something like asst_abc123). Names aren’t always unique. Make sure the assistant you're transferring to is live. If it's still in draft or hasn't been published yet, the system won't recognize it. Both assistants need to be in the same project or workspace. If they're in separate places, the handoff won't work — they have to “see” each other. Double check the destination type. If you're doing assistant-to-assistant, make sure you're not accidentally picking a Squad or some other route. No extra spaces or typos in the ID field. Easy to miss a hidden space when copying and pasting. Permissions matter. You need to have access to both assistants, or they won't show up as valid options. Try refreshing or reloading the tool. Sometimes it just needs a kick to register the change after publishing or connecting assistants.