I used my PayPal account to pay for Uber on two separate occasions. One was on May 15th and the other on May 16th. It shows that I made these purchases but I am not able to pay for them. The only thing that it shows that I owe is from a different purchase on the 18th. It says that my total amount due is $11.99 but it should be somewhere around $45. The amount of my available balance shows purchases but, again, I can't pay for them. Does anyone know what is causing this?