Did you have it set as 0 in the calculation type? Maybe let the action define the amount. Or put it as variable and let Rule Define it. If that does not work maybe try setting it as variable and use an expression in the rule.
It works just fine exactly as I showed you how to make it… one exception I did not mean for you to copy my action. You need to change Calculation Method to Rate from Ticket make sure Rate or Amount is 0. Max is 0 and Rounding is 0. Check Include Tax, Use Plain Sum, and Toggle Calculation. Then follow rest of what I told you to do. You probably need to log out and log back in for calculation type to take affect.