This is normal: you have 1 try every 3.5 days only if you travel to a real pyramid and speak physically to the pyramidkeeper. If you choose a virtual pyramid, then you can enter -free-1 attempt a month, if it´s wrong the pyramid is locked for 30 days.
The password checker needs credits. You can buy them if you are not sure about the right password and if you don't want to pay for a travel in vain.
I hope my explanations are clear enough