Let me test that. I'll be back.
Edit: Which rule are you using to apply item discounts?
Edit 2: I've tested it and it works fine for me. There might be two reasons.
1. There might be a typo. Check Trailing spaces.
2. Not every rules can access Ticket info. You can access Ticket data from rules related with tickets like "Ticket Closed, Ticket Created, Order Added, etc."