Why?

Is there some galactic conspiracy against me at my job? My manager Andrew says no.
Still, all the signs point to it sometimes; the lack of making money, the bad sections on good days, the good sections on bad days, the fact that my shifts are covered by other people before I even get to work.
It happened again today. I traded my evening shift with someone's morning shift last night because we are having the carpets cleaned tonight and we have to move furniture around. I was running late this morning and called in to let them know I was covering for this person and the hostess who answered told me that someone else was already covering this shift. So, needless to say, I was not needed at work. I can be at home not making any money.
On the bright side, I have already made progress on the whole furniture moving thing.