Seriously? 1 satoshi as miners fee?

What's so hard about sending 10000 satoshis inclusive with the transaction?
Because I just want to save the money (10000 satoshi in a 0.01 BTC transaction is a quite high percentage) in the fees and I had previously done this with no problem (it confirms within a day). But why this time I can't

All confirmation process are (maybe) random. So a success before don't mean a success now. Pay the normal fee next time if you don't want it to stuck too long.