iPhone 5s inductive charging at Starbucks

I tried to charge my iPhone 5s at Starbucks and it actually drained my battery and the iPhone would not even turn on!

Starbucks has that round inductive charger that plugs into iPhone and when placed on the charger on the table, a green light indicates the charging is on.

But my iPhone was drained and didn't turn on.

Did anyone experience this issue and/or did I do something wrong?

Andy