Just an FYI, if you are scheduled to work, by law you are owed at least 3 hours of work or pay for that scheduled day.
It may vary in different states and for different unions. Checking with your human resources department. Research your states labor laws.
I have heard several people complaining about showing up to work only to be told they are not needed for the day. It is the jobs responsibility to notify you before you leave for work if they do not need you for that day.
Some people have to pay to get to work. It would be an awful inconvenience to pay for parking ride then not have the opportunity to make that money back. It is also a waste of time, and I hate to waste my time.
If it is not the first time this has happened, you can ask to be paid for those dates too.