Im not sure I understand how you have your switches connected, but I think you need to connect them in parallel.
Sounds like you might have then connected in series.
Here is a drawing that shows them connected both ways.
this is only for one coin slot, you need to duplicate it for the other coin slots.
See if this looks familiar, if you dont have them parallel, try it.
Edit: Also double check the NO contact on the coin switch and your reject button switch.
The contact positions are backwards on my coin switches, from my push button switches. look on the switches' bodies for the NO mark. Make sure you are connecting to NO on both.