I can't open the casket in the crypt. Therefore I can't get the ashes for the voodoo lady. I went back twice to ealier saves but esch time the lid will not open. HELP!

have u got the right casket?

You're supposed to get the book off the Phatt Island mayor, or governor, or whatever, and you do that by Indiana-Jones-style trading it with a random book from the library. See, Guybrush needs a reason to open that casket, and he gets that from finding out what quote belongs to Rapp Scallion. I am aware of the fact that this reply must be like four years old, but at least people browsing this forum now will know the solution to your problem.