The reason why, is that there is the automated message informing the player that the game can not be played with bonus funds. Well, this might be the only thing I liked in this casino from my personal experience. By the time I opened up a slot, the balance was on the road to zero with no possibility of going up. I tried multiple slots, played every game on minimum bet, but the result was the same. Zero. Did not manage to trigger a bonus in any of the slots I played.
I changed around 15 slots. So I can definitely say I was not very impressed by the gameplay I had. Moreover, this was the reason my session was extremely fast.
Another thing I did not enjoy was the fact that I did not have a good time playing the slots. I did not trigger a bonus in any of the slots. After the bad time I had in this particular casino I decided not to play anymore here since I was very unimpressed by the slots and the unavailability of my favorite slots.