If none of those are the problem go into 'Edit Mod pack', then on the bottom left there is 'Open folder' click that and it brings up the mod list, then at the top press 'Monster' Then 'Minecraft'. Then I want you to press config, find an open the 'OpenBlocks' config, not openmods, openblocks. Then I want you to find "
# The id of the grave block
I:blockGraveId="
There is a number there that should be 2546. There you go
# The id of the grave block
I:blockGraveId="
There is a number there that should be 2546. There you go